Table of contents
It's been a while, TASVideos.
Game objectives
- Emulator used: Bizhawk 2.9.1
- Aims for fastest time
- Uses 2 players
- Plays at Hardest difficulty
- Does not abuse death or use continues
- Manipulates Luck
About this run
I didn't plan on making this run, having somewhat retired after my Metal Slug 3 run. At the time, I didn't think there were too much improvements that could be made for X2poet's run and the nature of FBA-rr (the only TAS emulator available for Arcade games at the time) killed any motivation. That began to change when I saw a 2 player speed run done by Topeng and Sukimos showing off some new potential strats. More new strats were developed by Metal Swag, who managed to push the 1 player level 4 time down to sub 15 mins (previous runs in this category were typically around 16 mins). These new developments and the release of BizHawk inspired me try to adapt the new ideas for a 2 player level 8 TAS.
This run manages to beat X2poet's by 10299 frames or 02:54.01. While roughly 30 seconds (~1800 frames) comes from opting to end input early, the majority of the improvements are from the main gameplay, using new strategies and optimizing everything better.
Note: I will be referring to some enemies (mainly tanks) by their official names that are given in the Metal Slug wiki.
Weapon Damage
- Pistol: 10 per shot
- Melee attack (knife, kick): 30
- Grenade: 100 (after the initial 100, the smoke can do 1 damage per 2 frames twice to certain enemies)
- H: 10 per bullet (pressing fire once shoots 4 bullets)
- 2H: 20 per bullet (pressing fire once shoots 4 bullets). There is a 2 frame delay that occurs in between rounds when you try to fire while standing (regardless of which direction you’re firing). This delay does not occur when you fire while crouched. Firing the first round while standing and the second round while crouching also eliminates the delay. Unfortunately, there are no workarounds if you need to shoot upwards.
- L: 8 per 2 frames (1 bullet consumed every 4 frames)
- R: 30 (against certain enemies, after the initial 30, the smoke can do an extra 30 damage 6 frames later, followed by two additional instances of 10 damage per 4 frames, resulting in a potential total damage of 80)
- D: 30 (the smoke can do an extra 1 damage to certain enemies)
- I: 30 (the smoke can do an extra 10 damage to certain enemies)
- C: 30 (the smoke can do an extra 10 damage to certain enemies)
- G: 100 (the smoke can do an extra 50 damage to certain enemies)
- F: There are two parts: the "main" flame and the "side" flame. The "main" flame does 20 damage per 2 frames while the "side" flame does anywhere from 0-5 damage per 2 frames. The "side" flame damage depends on how much it covers the enemy. The "main" flame can hit an enemy a maximum of 13 times for a damage of 260. The total max damage you can do with F is 314.
- S: 200
- Firebomb: 80 (The smoke of the firebomb can do 15 damage to other enemies that are close to the intended target)
- Slug Vulcan: 10
- Slug Cannon/Missile: 200
- Slug Crash: 400. There are two types of crashes that can be done. Crashing it right up against an enemy vehicle will cause a single explosion that does 400 damage. Crashing it while you're overlapping a infantry enemy (soldier, zombie, mummy) or on your own will cause the slug to rush forward (indicated by flashing red and jingling sounds). Against certain enemies, this type of slug crash is capable of dealing 400 damage per 2 frames as long as the slug hitbox is overlapping the enemy hitbox.
Note: Interestingly, big weapons cannot be obtained normally in this game.
Tricks/Glitches Used
- Turnaround Cancel
The main trick/exploit that separates Metal Slug TAS'es from speedruns. When you attack while crouching, you can immediately turn around and do something else. For certain weapons, you can immediately turn back around and attack again. This cancels the delay between time you fire a weapon once and the time you can fire again, allowing you to fire once every 4 frames. Useful for saving bullets with some weapons like H, 2H, and L. This can also be done with grenades and melee attacks. In fact, you can use it to alternate between using your weapon one way and throwing a grenade the other way. When doing this with melee attacks, you must wait 2 frames before turning around to cancel the attack animation, but it is still faster than just crouching and attacking.
- Faster H
Pressing fire once with H shoots 4 bullets, each doing 10 damage every 4 frames. It is possible to fire H such that the 2nd and 3rd bullets are bunched together, doing 10 damage every 2 frames. This is done by pressing fire -> waiting 4 frames -> pressing fire and down. This cycle can be repeated by using turnaround cancel and pressing fire again. You must shoot at least one bullet normally before you can fire two bunched bullets.
- Faster Vulcan
Pressing fire once with slug vulcan will initially shoot 5 bullets, each doing 10 damage every 4 frames. Depending on when you press fire again, the slug vulcan will shoot different amounts of additional bullets (ranging from 1 to 5) 4 frames after the 5th bullet. When you press fire on the earliest frame where the slug shoots 5 additional bullets, they will be shot 2 frames after instead, making it slightly faster. I’m not sure if this works with all slugs, but it worked with the two slugs that were used in this run.
- Damaging enemy vehicles with Nadia’s taser
Nadia is unique in that she will use a taser as her melee attack instead of knife. Like other melee attacks, it’s normally only usable against infantry enemies (soldiers, zombies, mummies). However, you can damage armored vehicles if there is a soldier near it by intentionally missing the soldier with the taser, but having the hitbox overlap with the enemy vehicle. This makes Nadia a must in this run as you will see that I get a lot of use out of this trick.
- Speed boosting off slopes
When jumping off slopes, you can a speed boost for a few frames. The amount of boost depends on which part of the slope you jump off of. In general, it’s not worth walking for a few frames just to try to get a bigger boost. Instead, you should ideally time/position your jumps beforehand such that you jump off the slope at the position that gives you the largest boost.
- Fast turret kill
In Mission 2 part 2, there are 5 turrets encountered that all normally have 750 HP. Three of them (first, third, and fourth) have a bazooka soldier hiding in them and contain a separate hitbox of 90 HP around the area of that soldier. Dealing 90 damage to that hitbox will instantly destroy the turret, saving a lot of time and ammo. Hitting that area requires precise positioning and can only be done with certain weapons.
- Amplifying cannon damage
The Metal Slug cannon normally does 200 damage to enemies. However if you manage to shoot through a soldier with a cannon before it hits an enemy vehicle, the damage dealt to the soldier will be added to the damage dealt to the vehicle. So shooting through one soldier can deal 400 damage, shooting through 2 soldiers can deal 600 damage, and so on. Used in missions 2 and 6.
- Using truck explosions to deal damage
When you destroy enemy trucks, the explosion deals a lot damage to enemies that are in its hitbox (I don't know the exact amount, but in Metal Slug 3 mission 5, it was enough to instantly reduce Allen's HP from 12750 to 1). Used in mission 4 part 1.
- Shooting F in a more diagonal trajectory
When you pick up another weapon while in the middle of a firing round with H (shooting 4 bullets), you will automatically fire a round with the new weapon. This is also occur while you're in middle of spraying H to shoot it diagonally. When you pick up an F while in the middle of spraying the H, you will shoot F in a more diagonal trajectory, will a slightly extended upward hitbox. Used in mission 4 part 3.
- Early release on cranks
When turning the cranks in mission 5 and 6, letting go of them early at a certain point will cause them to turn on their own and finish early, saving time.
- Skipping Di-Cokka tanks by stunning them offscreen
When fighting Di-Cokka tanks, hitting them with certain weapons (bombs, R, and S) will "stun" them and they won't move for a short period of time. Some Di-Cokka tanks will spawn while turning around and move offscreen initially. Stunning them while offscreen will cause them to despawn, allowing you to skip fighting them. Extremely useful trick since these tanks have a lot of HP in 2 players level 8 (1100 HP). Used in missions 5 and 6.
- Moonwalking
The most important trick in the entire series. Can be initiated by pressing up and then holding the key opposite of the direction you’re facing. The moonwalk can be extended by pressing up before the character turns back around. While mainly for entertainment, it does have some applications in saving time (mission 3).
Boss Notes
Metal Slug 4 is unique in that some of the bosses have interesting mechanics which are listed below. Two of these are disadvantages, requiring some workarounds.
- Full damage from weapon smoke
For some reason, the mission 1 and 5 bosses take full damage from weapon smoke. This means the R is able to deal up to 80 damage, making it one of the best weapons to bring against them.
- 100 HP blocks
The mission 1, 4, and 5 bosses have their total health divided into blocks of 100 HP. These bosses have multiple ram addresses, one that shows the total HP and one that shows the remaining HP in the block. Dealing 100 damage will clear the block and take you to next block. The caveat is that excess damage does not carry over to the next block. For example, if there is only 20 HP left in a block, throwing a grenade will only do 20 damage. What makes this even more complicated is that some of the bosses (or phases of the bosses) have multiple separate hitboxes, each with its own separate 100 HP block, but still sharing the same total HP. Though this can help me deal full damage with weapons more often because I can aim for the area that won't result in a damage loss.
- Taking damage from only one weapon
A few bosses have an interesting restriction where they can only take damage from one weapon at a given time. For some weapons, if both players fire at the same time, the damage from one of the weapons will automatically be buffered 2 frames later. In other cases, the damage from one weapon will override the damage from the other. This is the case for the final phase of mission 4 boss and mission 6 bosses (excluding Allen).
The last two mechanics mean that I have to be careful about when to use certain weapons. For many of them, I found it extremely helpful to use an Excel sheet to map out when to damage the boss.
Other Things to Note
- Turning the "Play Manual" off in the settings will skip the "How to Play" tutorial after inserting coins, saving 88 frames. Unfortunately, I didn't know about this until after finishing the run.
- Jumping has a higher max speed than walking, making it faster most of the time. Depending on the distance that needs to be covered, walking may sometimes be better than jumping.
- There are two types of jumps: standing (jumping without holding left/right) and moving (jumping while holding left/right). Standing jumps gain height faster, linger at the peak longer, and descend faster. Moving jumps gain horizontal speed faster. Both types of jumps still spend the same amount of time in the air (you will land on the same frame).
- Holding left/right for at least 2 frames before jumping will gain more distance than pressing left/right and jump at the same time. This means that whenever you enter a new area (whether you descend from a parachute (or ally helicopter for this game) at the beginning of a mission or walk in from the left), it’s better to hold right/left for 2 frames before jumping.
- When you’re exiting out of an area before a screen transition, it’s faster to jump out of the area rather than walking out of the area, it can save 4 frames.
- While firing pistol, H, or 2H upwards, jumping will cause the bullets to deal damage 2 frames earlier than if you had stayed on the ground since you’re closer to the enemy. However, as you land, there will be a 2 frame delay, reverting you back to the same rate if you had stayed on the ground. In short, when fighting enemies above you, jumping while firing the last round of bullets needed to destroy an enemy will allow you to destroy it 2 frames earlier. Before then, there's no difference between jumping and staying on the ground (though jumping might help reduce lag).
- Killing soldiers by disintegrating them causes the least amount of lag in almost all cases. This is usually done by using melee attacks. Explosions will cause the soldier to fly mid air, but you can still disintegrate them by hitting them with any weapon.
- When destroying aerial enemies (planes and helicopters), having them explode in air is faster than having them crash-land into the ground. Whether they explode or crash-land is up to rng, so this has to be manipulated.
- The rng in this game is determined by your inputs. Any input you make (even simple actions like holding right for 2 frames) can change the rng.
- There seems to be an rng element that determines when the screen will scroll after fighting certain enemies (mainly helicopters). It seems to be determined by how/when you destroy the enemy and the actions you do in between the time the enemy is destroyed and when the screen scrolls.
- Whenever the screen scrolls to let you move on, it's better to have jumping speed fully built up beforehand and jump with the screen scroll. It's around 2 frames faster than just holding right/left against the edge of the screen and trying to jump at the right moment.
Stage by stage comments
I spent a few extra frames to turn on the setting that displays the level at the bottom of the screen. It’s not necessary, but I thought it left no doubt to have “Level 8” displayed throughout the run (interestingly, Metal Slug 1 is the only one that has this on by default).
Like X2poet, I decide to use Nadia and Trevor as they are exclusive to this game (though Nadia is the only character who’s necessary). However, I spend 2 extra frames to select Nadia as player 1 and Trevor as player 2 (X2poet had them the other way in his run). This is because I found that having Nadia as player 1 puts her in a better position when entering areas, allowing her to reach enemies quicker to use her taser.
- Part 1
- I opt to use turnaround canceled pistol shots to destroy the first truck asap before moving to the right (the explosion also kills the remaining soldiers fast enough that the screen scrolls without an extra one spawning). While fighting the Melty-Honey, I kill the shield soldier on the left by timing a pistol shot such that it will hit the soldier directly when he spawns. The screen scroll after the helicopter must be manipulated.
- Part 2
- The plan for this mission was to take at least 100 bullets of 2H + all 30 bullets of R to the boss battle so I used a lot more grenades in this section, saving a lot of time. After fighting the Melty-Honey, I was able to get the screen to scroll faster by killing the two soldiers on the left simultaneously (killing the first one will cause two extra ones to spawn, which is what happened in X2poet’s run). After destroying the last tank (Di-Cokka), I found that you don’t need to ascend the stairs asap. The screen transition is only affected by lag as long as you get there fast enough. Walking up the stairs seemed to create the least amount of lag, so I kept the jumping to a minimum (only did it once with Nadia to get to the end fast enough to get the screen to transition asap).
- Boss - Brave Guerrier (1300 + 1400 + 2200 HP)
- All three phases of the boss have at least one 100 HP block. For some reason, the total HP of the first and third phase are stored in an address outside the range where most enemy HP values are stored, the lua script by mtvf1 wasn't able to find it on it's own and so I had to find it manually with ram search. All three phases aren't destroyed until the HP is "below" 0 (e.g. if the boss has remaining HP is 10, hitting it with pistol won't destroy it, but if it's 9 HP, a pistol shot will destroy it), meaning we need at least 1 extra damage for all the phases. For the first two phases, we're able to get it from the grenade smoke while for the third phase, we just get it from an extra shot of 2H or H.
The first phase is still the least clear to me. There's one 100 HP block, which is affected when you hit the blimp directly. There are also two turrets and a mine launcher, which are not affected by the 100 HP block, so you can hit them for full damage. When using R, it's better to aim for them since they're closer to the ground. When you hit the turret with R, the smoke is still able to hit the blimp, affecting 100 HP block. For some reason, trying to hit both turrets simultaneously caused me to lose damage. There were other times where I would lose damage even when the 100 HP block seemed to indicate that I wouldn't. There might be something that causes some of the damage to not register if you try to deal too much at once (Also seen in mission 5 boss). Ultimately, I settled with using R at moments when it would do the full 80 damage while using 2H continuously. Since it has 1300 HP, the plan is to use 1 grenade + 8 shots of R + 7 rounds of 2H. I had to delay using 2H at the start to get optimal damage out of the first two shots of R, but it turned out that aiming for the blimp directly with 2H gave me the perfect amount of delay.
The second phases has two 100 HP blocks, the two hitboxes seem to be divided right on the left side of the "A" logo. It has 1400 HP, so the plan is to use 2 grenades + 10 shots of R + 5 rounds of 2H. I use the grenades at the start because they can be thrown a little beforehand and allow me to still use R and 2H on the earliest possible frame. By "wiggling" in between the two hitboxes, I was able to maintain full damage while firing both weapons asap. By far the simplest phase out of the three in this fight.
The third phase only has one 100 HP block and unfortunately, there's no way to avoid hitting it. So we have to work around it as best as we can with our weapons. The missiles are also manipulated to go to the left so they don't hit Trevor. I start off by using my remaining grenades because there won't be an opportunity to jump and throw them later for full damage. I used an excel sheet to determine the ideal times to use my weapons. Since there's no way to avoid hitting the 100 HP block, some damage loss is inevitable, but I try to keep it to a minimum. The second jumps that Nadia and Trevor do in this phase were deliberate and necessary for timing my weapons (remember, jumping accelerates 2H bullets by 2 frames for a brief amount of time). Once I run out of R, I pick up the H and finish off the boss.
When this boss is defeated, the characters initially have to move to the left for the POW tally to start asap, which is why I jump towards the left (jumping also allows me to destroy the boss 2 frames faster). However, there is a small window where I can jump to the right and still have the POW tally start asap. This saves time since it allows Trevor and Nadia to enter the ally truck faster.
- Part 1
- X2poet skipped using the slugs in the 1st half of this section, but I found that the enemy vehicles had too much HP for it to be worth skipping them. The other problem is that skipping the slugs leaves me only with H + pistol when fighting the planes in the 2nd half. Topeng and Sukimos opted to take one of the slugs to combat the enemies better, which I also decided to do. They used the Bradley in their run, but I opted for the Metal Crow (Melty-Honey) in this run. Its "cannons" (missiles) act like C while still dealing 200 damage and can be manipulated to hit the right targets, making it the better option. Despite the slug moving slower, more time was gained from being able to destroy enemy vehicles faster. I thought about taking both slugs, but decided it wasn't worth it. I would have to exit one of them to pick up the bomb crate, which takes too much time. And we have enough R and 2H to provide roughly similar firepower as a single slug. When I destroyed the two helicopters, I initially tried to make both explode, but found that letting the lower one crash-land gave me the best rng to make the screen scroll asap so I kept it that way.
The other benefit of taking the slug is that it allows me to save 2H and use it in the 2nd half of this section and the next part. The planes have 80 HP and the 2H deals 80 damage per round, making it the perfect option against them. I manipulated the planes to move to positions that allowed me to destroy them asap. It's fortunate that in this segment, lag only occurs when the planes explode, so I could use H liberally to help destroy the planes asap. At the end of this section when I get off the truck, it actually didn't matter where I jumped off from, the screen transitioned at the same time.
- Part 2
- Here, we really get to see the benefits of using 2H in this section, as I'm able to destroy all the enemies much faster. Later at the incline where you fight the 4th and 5th turret, destroying the 5th one (on top the incline) first gets the screen to scroll asap. Near the end where I fight the Sarubia, the screen will normally stop and I have to kill two soldiers that walk in from the ledge on the top left before it scrolls again. Those soldiers can actually be killed beforehand, but doing so causes two more to walk in after the screen stops. However, I can manipulate the screen position by having Trevor stay behind the slug and make the Sarubia spawn first and destroy it before the screen stops. This prevents the two extra soldiers from walking in and the screen continues to scroll, saving time. I have to use a cannon to destroy the tank, but this is no problem. 9 cannons are enough for the boss and using vulcan causes a lot of lag in this section.
- Boss - Toschka Dalanue (3600 + 4800 + 5400 + 4800 + 4200 HP from lowest to highest segment)
- One interesting note about this boss is that each segment will be destroyed once its HP gets below less than 1/6 of its total value (e.g. the first segment will be destroyed once it has less than 600 HP). The fight ends when the top segment with Allen is destroyed, but we must destroy at least three out of the first four segments before we can deal damage to him. The third segment has the most amount of HP, but there's no good way to skip it, so we opt to skip the fourth segment instead. In this fight, it's possible to hit two segments at once with cannons, grenades, and slug vulcan to effectively deal double damage. Interestingly, the 2H and H are not able to do this. By taking advantage of this, I'm able to destroy the first two segments quickly while also dealing good damage to the third segment at the same. Once the first two segments are destroyed, I finish destroying the third segment and end the fight with the remaining grenades, 2H, I, and pistol. Thanks to the new strats I used in the previous parts, I was able to bring 17 more grenades to this over X2poet's run and by taking advantage of double hitting segments, I was able to save a lot of time in this fight.
- Part 1
- By moonwalking with Trevor, I'm able to build full speed while facing backwards and lose a lot less speed by not having to turn around to use H to kill the parachuting bazooka soldiers.
- Part 2
- The truck causes a lot of lag after it spawns. I could use 2 grenades to destroy it faster to eliminate it, but after some testing I found that I need to save all my grenades for the boss. Using H while the truck is present also causes a lot of lag here, so I tried to minimize its usage (only used it to destroy the truck itself). The main priority is getting the screen to scroll asap after destroying the truck. The key is killing two soldiers that walk in from the left after the truck spawns. The soldiers spawn at the same time regardless of when the truck is destroyed (and it can be destroyed with just H and pistol well before the soldiers spawn), but the way they walk in affects when I can kill them (and subsequently, when the screen scrolls). Manipulating them to walk in fast allows me to kill them fast and get the screen to scroll (hard to notice since they are still killed offscreen). Once this screen scrolls, the rest of the section only has been done fast enough. The tank will spawn at the same time as long I get there early enough and the screen will scroll at the same time as long I destroy it fast enough (only variation coming from lag). So I prioritize minimizing lag the rest of this section. I also pick up I with Trevor as it turned to be more useful than S in the next part.
- Part 3
- The main goal in this section is to get both players on the log asap. I tested taking the firebombs vs not taking them. Somehow, taking the firebombs ended up being faster than not taking them. Waiting for the firebombs requires Trevor to initially hang back, which causes the planes to spawn later and shoot missiles later, allowing Nadia to continue jumping through them better (only have to destroy the missiles with I). Trevor also somehow ended up in the perfect position to take advantage of boosts off the slopes, allowing him to gradually make up the lost distance from having to wait from the firebombs. Skipping the firebombs caused the planes to spawn earlier and shoot missiles at bad times, requiring the characters to sometimes walk before being able to jump again or destroy the planes (which caused a lot of lag in this section). I tried giving Nadia the S and Trevor the F, but the timing of the planes spawning and shooting the missiles was still a problem when I skipped the firebombs. Bouncing off the enemy tanks is actually slower (results in a slower speed in the air), so it's better to destroy them to continue jumping normally.
Once I get on the log, I used the I to kill some soldiers by disintegrating them to reduce lag.
- Boss - The Iron (6500 HP)
- The only real normal boss in this game with none of the unique mechanics. The F is able to deal the full 314 damage to it. On paper, 10 F shots + 20 bombs + 18 firebombs should be enough to destroy it, but when you use grenades together with F, some of the side flame is lost (which is normal across all the Metal Slug games), requiring me to bring the full 20 bombs and 20 firebombs. The firebomb smoke is able to deal full damage (80) to the helicopter, so I make sure the helicopter explodes when it's destroyed to save lag frames. After firing the final F shot, jumping towards the left with one character will position both characters slightly more to the right during the POW tally, which saves a bit of time when they walk towards the ally truck. If I jump with both characters, one of them will be pulled significantly more to the right, but the other one will be pulled significantly more to the left, so this ends up being slower.
- Part 1
- I opt to use grenades to destroy the first Di-Cokka faster. It's also better to use turnaround-canceled pistols immediately than to try to use the walk machine slug. The two Girida-O tanks in this part have their hitboxes overlapping with a truck, so they can be destroyed faster by destroying the truck (650 HP vs 320 HP). The second one will sometimes move forward so it had to be manipulated to stay still and fire shots. There are two pairs of helicopters in this part. Each pair is manipulated to group together so I can hit them both with a single grenade, which is all that is needed to destroy them fast enough to get the fastest screen scroll (which also has to be manipulated). Normally when using a slug, it's faster to jump with it, but this is not the case for this slug (hence the name "Walk Machine?")
- Part 2
- The main priority in this part is to keep the slug moving before I crash it. I use the slug vulcan to target the zombies on the building while Nadia targets the ones on the ground. Once the slug is far enough to the right where it can't target the zombies without stopping, I have it switch to killing the zombies on the ground while Nadia kills the remaining zombies on the building with H. Afterwards I crash the slug much earlier to kill the zombies on the right earlier. If you do this and destroy the truck that spawns on the left fast enough, the screen will scroll immediately without additional zombies spawning. I opted to only use grenades to destroy the truck so that Trevor and Nadia can keep moving to the right. This saved about 120 frames over the next best strat I found which was to crash the slug while overlapping with a zombie so that it hits the truck twice while rushing to the right and killing the other zombies. Though I end up losing nearly all of that in the boss fight later due to having to use F 2 more times since I have 6 less grenades.
- Part 3
- By delaying the kill on the soldier zombie, I can get the screen to scroll after just killing one zombie. If you kill it too early, it spawns another zombie that must be killed before the screen scrolls, which is slower. When picking up the F, by shooting it diagonally, I can clear the first wave of zombies much more efficiently with 2 shots of F rather than 3. At the end after I destroy the "Danger" barrel, the screen scroll must be manipulated. Fortunately, only one of the players needs to exit the screen asap so I'm able to pick up the H without losing any time.
- Boss - Big John (700 + 800 + 4800 HP)
- This boss consists of three phases. The first two phases of the boss behave normally so I use F and H to destroy it asap. During the first phase, by luring the metal claw to the left, I can destroy it before it does an attack (the claw is invulnerable when it does an attack). During the second phase I move toward the right so I can attack the third phase asap. The third phase exhibits some of the unique boss characteristics. It has two separate 100 HP blocks, one for the face and one for the left(?) arm that shoots missiles. Only the one covering the arm is relevant since we spend the rest of the fight dealing damage to it while crouched. The third phase also takes damage from only one weapon at a time, so the best way of dealing damage is using only F (20 damage per 2 frames). Using H overrides any damage done by F. In between each F shot, there is a 4 frame window where the main flame is not doing damage, this window is just large enough to squeeze in two bunched H bullets, which is more damage than two instances of side flame damage. However, in order to bunch H bullets we need to fire one shot normally and since we don't to want to override any main flame damage, we fire the first shot to the left before turning around to shoot the two bunched bullets in the 4 frame window. When the 100 HP counter is at a full 100 at the start of the 4 frame window, I throw grenades instead. This way, I was able to destroy this boss with only 16 F shots, 6 grenades, and 36 H bullets while X2poet needed significantly more resources due to using H/pistol at the same as F.
After shooting the final F, I time a jump to the right so that Nadia and Trevor don't have to walk to get inside the crate. I thought it would save a good amount of time, but it actually ended up saving only 3 frames... (most likely that it actually saves 4, but 1 frame lost to lag). Pretty disappointing, but we take it.
- Part 1
- The plan for this mission is to use R against the boss, which frees up grenades to be used in earlier parts of this mission. When fighting the first Di-Cokka, going right up against it will cause pirates to periodically charge in from the left and you need to kill multiple of them before the screen scrolls. By hanging back a bit, I can delay the timing of when the pirate spawns, allowing me to destroy the Di-Cokka and the crates uninterrupted and making the screen scroll after just killing one pirate from the left. I also opt to use a grenade to destroy the 1st Melty-Honey, it's faster than using R, which is better suited in the 2nd part. The 2nd Melty-Honey can be destroyed with pistol, it's fast enough to let Trevor keep moving uninterrupted to the right to the crank.
- Part 2
- An autoscroller part. At the first stop, if you kill the shield soldier + pirate on the left and the pirate on the right fast enough, you can get the elevator to move again immediately. I thought you had to use R to kill the enemies on the left, but it turned out you can get the elevator to move again at the same time using only pistol.
At the second stop, there are two Di-Cokkas that spawn from either side. The one the left can be skipped by stunning it offscreen with R or a grenade, saving a lot of time. After that, there's a Sarubia and a Melty-Honey and that must be destroyed before the elevator moves again. Ideally, you want to start damaging the Sarubia while at the right end to get more damage in before the Melty-Honey spawns, but the extra distance causes large amounts of lag. However, I found that destroying both too early causes an extra soldier to spawn, which wastes time. So it was better to delay destroying them to prevent the extra soldier from spawning. I use that necessary delay to initially position the characters closer to the Sarubia and slowly move to the right to attack the Melty-Honey. This helped reduce lag overall while not costing in game time.
At the final stop, there is a Bradley that must be destroyed and some soldiers that must be killed before the elevator moves. The number of soldiers that need to be killed can be kept to a minimum by delaying when you kill them, but it also depends on how fast you destroy the Bradley. I found that dealing at least 600 damage with G and grenades keeps the required number of soldiers killed at a minimum, but using an extra G or grenade to deal 700 damage got the elevator to move earlier. Interestingly, using all G and grenades to destroy the Bradley asap was slower for some reason. With proper delay, you can get the elevator to move after only killing 5 soldiers (3 from the left, 2 from the right). You can actually delay killing the soldiers on the left a bit more to only have to kill 2 instead of 3, but this did not gain or lose time.
- Part 3
- The first Melty-Honey does not have to be destroyed asap, the main priority is actually killing the soldier on the top right asap, which I do by bouncing off the Melty-Honey with Trevor to gain enough height to shoot him while Nadia destroys the Melty-Honey with her taser to save G bullets. The same goes for the Di-Cokka, you just have to destroy it before the killing the three soldiers that descend from the rope. I still used Nadia's taser to speed up destroying the Di-Cokka because using pistol for a long time starts to cause lag even when Trevor is right up against the tank. While getting ready to fight the helicopters, I rescue the POW that gives R. I pick it up while spawning the first pair of helicopters with the plan of taking it to the boss. It's possible to double hit each pair of helicopters once with a G, saving me time and bullets. I also used grenades to destroy them faster, which also allowed me to have enough G bullets left to destroy the last helicopter. As always, the screen scroll after destroying the second pair of helicopters must be manipulated. After destroying the last helicopter, if you kill the first parachuting bazooka soldier, the two soldiers on the crate, and the two soldiers at the top next to the motorcycle fast enough, you can get the screen to scroll immediately. However, killing the parachuting soldier too fast causes a 2nd one to spawn, so it must be delayed a bit.
Before going to the boss, I need to pick up a H for Nadia, which I have two options for: the crate from where I fought the last helicopter or the POW right before the end of this section. After testing both options, I found that getting it from the POW was faster, but not by much (~8 frames). Skipping the H to use pistol with Nadia results in a slower boss fight.
- Boss - Sea Satan (4 * 1100 HP)
- Interestingly, the total HP of this is boss is stored as four separate 1100 HP segments. The boss itself has four separate hitboxes, each with its own 100 HP block. They are roughly: the left side of the main body around the fins, the right side of the main body, the deck, and the gatling turret. Similar to the first phase of mission 1 boss (I think), this boss has the unique property where if you try to do too much damage at once with your weapons, sometimes the damage will just not register even if you aim at separate 100 HP blocks. I'm not sure why this happens because boss doesn't necessarily have the restriction of only taking damage from one weapon, there are instances where I'm able to damage it with R and H/pistol simultaneously. From more testing, I found that grenades will always override any other simultaneous damage so I made sure use them at moments where they were the only source of damage. Using turnaround canceled R on its own resulted in some of the damage not registering. I found that the best way to approach this boss was to stagger the R and fire at moments where it deal 70 or 80 damage while using H to manipulate the 100 HP counter to ideal numbers. Most of the time I could fire R once every 6 frames, but there were a few times where I had to wait longer before the R dealt good enough damage (Using an excel sheet to keep track of everything was extremely helpful for this). By the time the first missiles were fired from the turret, I was able to get through three of the four 1100 HP segments, so I could get through the last segment by manipulating a bomb crate from the missile and finishing off the boss with grenades + H.
- Part 1
- The main priority is to keep moving down uninterrupted and have one of the players reach the bottom asap. Killing certain soldiers asap will make the screen scroll immediately without having to kill the bazooka soldiers that parachute from the top. I also used the strat developed by Metal Swag and Sukimos, where I pick up the extra grenades after picking up the firebombs to maintain having regular grenades. Sometimes I had to briefly stop to avoid picking up certain items too early. At the end it didn't matter where Trevor landed as long as Nadia landed as close to the exit as possible.
- Part 2
- I thought about using R here instead of C, but it ended up being slower. It's not necessary to kill all the soldiers at the end with C (you only have to kill the first few that spawn), but I still went for it for entertainment.
- Part 3
- A single grenade is all that is needed to destroy the 1st Melty-Honey and the two Mortar soldiers (the 2nd one doesn't spawn until the 1st one and the soldiers are killed). I still use C to disintegrate the soldiers to reduce lag.
- Part 4
- Main priority here is to kill the last shield soldier, the two soldiers that descend down the rope on the left, and the two soldiers that spawn on the right crate. I destroyed the two cameras with Nadia's taser for fun.
- Part 5
- I opt to only use S and grenades to destroy the two Sarubia's, the plan is to take all 30 bullets of F to the boss. Using only S and grenades also helps save lag frames.
- Part 6
- It's important to start turning the crank for the bomb crate early, but it's also important to spawn the Bradley so I can start attacking it asap. It was best to have Nadia rush forward with the S to destroy the Bradley while Trevor moves forward just enough to spawn the Bradley before backtracking to the crank. By destroying the Bradley asap with S + grenades, I'm able to get the screen scrolling without having to kill some extra soldiers. At the incline, you can get the screen to scroll immediately by killing the soldiers on the left asap. I used a grenade because backtracking to use knife takes way too long and it's better to keep Trevor moving forward to spawn the next group of enemies asap.
In the last fight of this section, the screen will only scroll after the second pair of soldiers have descended down the ropes, which is why it's important to spawn them asap. The crates here all have 350 HP, I have just enough time to destroy them with 3 grenades + 2 melee attacks and make it over to the right to exit the section asap.
- Part 7
- It's best if the first Di-Cokka is destroyed asap, the next one doesn't spawn until the first one is destroyed completely (including the soldier who exits it). There are two Di-Cokka's that spawn on either side afterwards, the one on the left can be skipped by stunning it offscreen with a grenade or S. The one on the right only needs to be destroyed fast enough and the soldier exiting it doesn't have to be killed, the screen scrolls at the same time (with only lag affecting the timing).
- Part 8
- If I had L, I would've considered skipping the Metal Slug as well. However, with F + S, there's no efficient way for me to kill some of the soldiers in this part. Fortunately, after some testing, I found that taking the Metal Slug only costs around 120 frames while saving me a lot of ammo and grenades, which saves me more time in the final boss.
The first Melty-Honey doesn't have to be destroyed asap, I can destroy it with the Metal Slug cannon and the Sarubia will still spawn at the same time. The Di-Cokka later also doesn't have to be destroyed asap, the screen will only scroll only after all the soldiers have spawned on the left side. After destroying the first Morden robot, delaying to kill the soldier on the left prevents an extra soldier from spawning and gets the screen to scroll faster, but this must also be manipulated. For the final 3 Morden robots, I use S to destroy the one the left and cannons to destroy the two on the right (waiting for all three of them to group together to destroy them only with cannons takes too much time). Interestingly, I only had to destroy only one of the robot heads on the right (the other one got despawned) and the one on the left could only be hit when the Metal Slug was all the way on the left side of the screen (maybe because it was too far off screen). Destroying the left Morden robot 2 frames later can get the head closer to the screen, allowing it to be destroyed a few frames faster, but it didn't get the screen to scroll faster (which also had to be manipulated).
Rescuing the businessman costs 430 frames, which takes too long and not worth it even with F. I delay jumping with Trevor off the "Danger" barrel, this allows Nadia to get in one more jump to exit the screen in jumping speed, which is faster (you only need one of the characters to exit to start the screen transition for this part, Trevor could've walked the rest of the way and the screen would've still transitioned at the same time).
- Boss - (fake) Allen O’neill (1100 + 1100 HP)
- There are two phases in this fight. During both phases, Allen will only take half damage from grenades (this is also the case in the other games) so I only use S and F in this fight. Getting too close to him will cause Allen to knock the player with a melee attack, causing them to lose their weapon. For both phases, 3 shots of S + 2 shots of F was the best combination. I could use 2 shots of S + 3 shots of F, but that loses more time in the final boss due to having less F. Using 4 shots of S + 1 shot of F is also viable, but that loses more time in the Allen fight because the S is a slow weapon.
During the first phase, Allen is manipulated to walk to the edge of the platform and fall off, this allows Trevor to jump and deal nearly full damage with F quickly. During the second phase, I manipulate Allen to stay on the ground, his death animation only starts when he's on the ground. After his death animation, the screen scroll must be manipulated. I found that standing still got the screen to scroll the earliest.
For some reason, it was actually faster to have the players land in front of the elevator and walk to their final positions inside rather than trying to land directly in the final positions inside the elevator. It could be that there's some timer that only starts when the players are touching the elevator which would explain why it was faster to do it that way.
- Final Boss - Amadeus Mother Computer (5500 + 5500 + 10500 HP)
- All three phases of this boss can only be damaged by one weapon at a time. The first two phases also only take half damage from grenades, so it's best to use only S and F for them. Interestingly, firebombs still do full damage, but I don't think it's worth converting to firebombs just for that as the previous sections would all be slower. Plus, the leftover grenades are still needed for the final phase.
The fastest combination for the first two phases is 10 shots of S + 14 shots of F, which we're able to do for the first phase. I was only able to manipulate the missiles to drop 2 H unlike X2poet, who got 4. Fortunately, it turned out that I only need two (and getting less H from the missiles saves a bit of lag). Since the boss can only take damage from one weapon, some of the main flame damage is occasionally lost whenever I use S. I tried to mitigate it by timing my shots such that I'm able to do damage with some shots of S in the 4 frame window between F shots (Excel sheet ftw).
Since we're only able to to bring 26 shots of F, we have to settle for using 12 shots of S + 12 shots of F for the second phase, which is slightly slower, but not by much. The main priority is to fire all shots of S asap, since we're able to do enough damage to bring the boss HP down enough that the 12th S shot will destroy it. Using pistol after running of out of F was more than enough and allowed me to have full H bullets for the final phase of the boss.
The final phase of the boss takes full damage from grenades, which is why we save our remaining grenades for it. During this fight, the boss will spawn two robots on either side which are capable of dropping extra grenades. In 2 players level 8, the boss spawns six robots in total, meaning we can get six extra grenade drops. However, they only spawn after Amadeus does the pink laser attack, so it is manipulated to do so. During the first attack and the time it takes for the robots to spawn, we can use H to bring its HP down to 6900 and use the extra grenades to finish it off. I tried my best to manipulate the drops while destroying the robots asap, but I often had to delay attacking to get the right manipulation (the missed H shots while destroying some of the robots were necessary to get the right manipulation). It seemed like destroying each robot at separate times was better, destroying multiple robots near the same time would result in only one item drop.
Ending Input Early
I opted to end input early. The only difference in the two endings is the cutscene that plays after the final POW tally up. Ending it early like this also allows the run time to be more comparable to RTA timing (which ends the moment Amadeus is destroyed). If there's a new TAS that manages to beat Amadeus earlier than this TAS, but gets a "slower" time from doing the extra section, it should of course obsolete this run.
Improvements
- I didn't know that turning the "Play Manual" setting off allows you to skip the "How to Play" tutorial, saving 88 frames. Unfortunately, this game isn't too hex edit friendly due to lag (and it changes the rng). It should be done in all future Metal Slug TAS'es.
- There might be areas where lag could be reduced better
- There might be luck manipulation in some areas (screen scrolling, final boss drops)
Thanks
- X2poet, for his TAS. No matter how improvable his runs end up being, he deserves a lot of credit for setting the bar. It's amazing that he managed to TAS the entire arcade entries in a year with FBA-rr. Huge respect.
- Topeng and Sukimos, for their 2 player run.
- Metal Swag, for his work in pushing the 1 player category to its limits.
- mtvf1, for writing the lua scripts, which I adapted for BizHawk.
- mamuuuut for pointing out that the tutorial can be skipped, even if it didn't make it in this run.
- Developers of BizHawk. It's amazing how optimized Metal Slug TAS'es can be when you're able to use TAStudio.
nymx: Claiming for judging.
nymx: As stated in the submission, I'm also surprised that X2poet's run could be improved so much. X2poet's run was a destructive force, but this run takes it even further. Watching side-by-side, you make quick work of things and exit each stage with shocking improvements. All I can say is that I congratulate you on this effort! It was a really great effort and an unexpected surprise! :)
Accepting over #3257: X2poet's Arcade Metal Slug 4 in 17:11.97.
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