Even if speed of flying is listed as 10, flying has acceleration, unlike all others. This gives all sorts of interesting problems with which method is actually the fastest.

Note that dropping down does not preserve horizontal speed and is in general very slow horizontally (vertical speed goes very high).

• Every level starts with 100% health
• Any hostage resuced resets health to 100%
• Any food item picked adds 25% health up to 100%
• Each enemy type has its own damage amount it does on contact (also applies to boss attacks)
• * Basic male and female zombies do 15%
• * That fat male zombie does 45% (ouch)
• * Those slow spiky enemies do 30%
• Some enemies may in some conditions do damage diffrently from normal. Like spiky enemies sometimes do only 15%.

Dispenser: F, free.

Pros:

• Cheap to use

Cons:

• Really pathetic damage

Verdict: Don't use unless there is no alternative.

Dispenser: P, 15 credits / 11.

Pros:

• Damage potential is adequate
• Hits barrels

Cons:

• Expensive
• Often can't hit enemies at all or at least not without ducking or otherwise slowing down.

Verdict: Expensive, but sometimes useful weapon.

Dispenser: G, 15 credits / 6.

Pros:

• Really high damage (there are precisely two damageable things that can survive it)
• Really good for destroying Alien Generators (even if it doesn't contact explode when hitting those)

Cons:

• Unsable in narrow corridors
• Usually can't reach the target before Harry plows into it.

Verdict: The second most useful weapon.

Dispenser: M, 20 credits / 6

Pros:

• Also really high damage (no enemy it can target survives that)
• Seeks enemy, so doesn't have to be aimed.
• If there is no enemy on screen, fires straight forward

Cons:

• Often locks into wrong enemy.
• Often can't reach target before Harry plows into it.
• If the targetted enemy dies, wanders off in weird directions.
• If there is no enemy on screen, fires straight forward.
• BUG: Sometimes damages but doesn't kill the enemy. The missiles will then ignore said enemy.
• Can't target barrels.

Verdict: Despite the shortcomings, this is the most useful weapon.

Dispenser: N, 20 credits / 1

Pros:

• Really high damage (only 2 enemies can survive direct hit)

Cons:

• Long countdown
• Expensive

Verdict: Useless, except for destroying Alien Generators if one does not have thermo-grenades.

Pros:

• Extremely powerful (even higher damage than missile, grenade and nuke)

Cons:

• Expensive

Verdict: Useless, except for some special circumstances (2-2, 4-1).

Amount of Missiles and thermo-grenades rounds up(!) to nearest multiple of 6 (anti-carryover).

Amount of photon blaster shots rounds up to nearest multiple of 11.

If you use memory corruption to give yourself some other weapons:

• Photon blasters are marginally better than flamethrower
• Missiles can't target boss, and there is nothing to explode them agaist, so these can't damage the boss at all
• Contact explosion by thermo-grenade doesn't work. Timed explosion does, and can hit bosses in missions 1, 3 and 4. Mission 1 and 4 bosses survive one hit (second hit kills those). Mission 3 boss is killed by the first hit.
• Micro-nukes, pretty much the same as for thermo-grenades (except these don't have contact explosion)
• Omega takes bosses down to 0HP but does not kill. Then flamethrower or photon blasters take health to negative values. When health reaches -12HP, the boss dies.

For Mother Alien, this duration is barely long enough to exploit, even with help from the forward current. Jump slam attack of THX 1138 is much longer.

Less severe version of this appears also with Alien Leader: While the leader is swinging the microphone, the boss hitbox is replaced by microphone hitbox.

This is only known to be possible in 2-1 and 3-3 and for neither it saves any time.

There is counter associated with the boss. If health subcounter (which cycles every 12HP of damage) hits zero while enemy counter is odd, the boss won't take damage. If it is even, the boss takes damage.

• Jumping small aliens
• Zombies (except for cyberzombie and fat woman zombie)
• Those spiky slow enemies
• Wandering slimes

If you kill respawned enemy, you won't get a credit for it.

However, the enemy AI is affected by Harry's position and actions in really convoluted way. This has nasty tendency of runing improvements by making enemies move to stupid positions.

• Number of hostages is exact, since you must rescue all hostages to proceed.
• Number of switches is number of switches flipped. Not all switches may need to be flipped (those might open shortcuts or bonus areas, or it might be possible to use glitches to get around flipping it).
• Number of generators is the number of generators destroyed. Possible generators opening secret areas are not counted (none are known currently).
• Length of level is counted from first frame teleport-in animation starts to first frame screen begins to be blacked after level completion (exception: 4-5, where length is to input cut-out).

With any sort of faster computer (err, what isn't, some sort of 286?) turbo play makes the game so fast that it is difficult to play (and of course, ups the speed for the TAS).

I also disable page flipping via commandline switch. This causes some tearing, but some tearing is far perferable to blinking that would occur if I hadn't disabled it.

There are also some additional logos, but I skip these.

Narration: "Space Station Liberty"
Narration: "High above earth [2030AD]"
Diane: "Greetings Harry. Glad you could make it."
Harry: "I came as fast as I could Diane. What's up?"
Diane: "Three days ago an Alien ship entered Earth's orbit."
(Cutscene of alien ship dropping from warp.)
Diane: "It landed in New York City, attaching itself to the Big Corp skyscraper.
Diane: "We don't know where the Aliens came from, but we do know that they're turning innocent people into mindless zombies."
(Still scene showing alien, scared human female, with some sort of container with green stuff and human skeleton.)
Diane: "We believe that they plan to use earth people as slaves in their quest to take over the galaxy."
(Cutscene showing woman (looks like the same one as in the earlier picture) being transformed into zombie in some sort of chamber.)
Diane: "Here's a transmission that we received from their leader."
Leader: "Greetings Earth scum..."
Leader: "You have 24 hours to turn control of the planet over to me, or I will begin turning my hostages..."
Leader: "Into brain-dead killer zombies!" (with still picture of two zombies, one evidently had been male and other female).
Harry: "What a diabolical plan!"
Diane: "We sent some operatives to rescue the hostages and destroy the alien ship..."
Diane: "...but they failed."
Harry: "What happened to them?"
Diane: "We can only guess. They've probably been turned into slobbering mindless zombies by now..."
Harry: "Those fiends!"
Diane: "The radiation level is too high to maintain constant radio contact."
Diane: "But I can make occasional contact via Info Disk Signal Boosters left behind by previous agents."
Diane: "After you rescue all the hostages, make way to the elevator that's located on each level."
Diane: "Any questions?"
Harry: "What weapons do I have?"
Diane: "You have your Flame Thrower and some Heat Seeking Missiles initially,"
Diane: "but there are a number of Personal Offensive Weapon dispensers thought the area."
Diane: "You'll be able to gain access to Micro Nukes, Thermo Grenades, Photon Blasters..."
Diane: "and the awesome OMEGA!"
Harry: "Sounds righteous Diane!"
Diane: "Harry, the future of the free world depends upon you."
Diane: "Good luck."
Harry: "I'll do my best."

Narration: "Back at Starbase Liberty..." (yes, the first intro says "Space Station", this intro says "Starbase".)
Diane: "Our recon drones have secured valuable data on the Alien ship."
Diane: "It literally merged itself to the top floor of the Big Corp skyscraper,"
Diane: "and any approach by air has been met with deadly resistance."
Diane: "It appears that the only way to get close enough is via the city sewage system."
Diane: "We want you to transverse the sewers freeing any hostages that they may have taken,"
Diane: "And locate entrance to the Big Corp factory at the base of the skyscraper."
Harry: "Is there anything I should keep an eye out for?"
Diane: "There are numerous pods containing Aliens scattered throughout the sewers."
Diane: "Also, keep an eye out for the Mother Aliens..." (with picture with text "Mission 3" (sic!).)
Diane: "They spit lethal space slime."
Harry: "I'll do my best to keep clean."

• Hostages: 9
  
• Switches: 4
  
• Generators: 0
  
• Length: 44.474s (3117 frames)
  

If I seem to miss some edge by fair margin, that's because controls and physics are quite bad (especially in turbo mode).

My plan is to buy total 3 packs of missiles for mission 1, one in 1-1 and two in 1-2. There are no useful weapon dispensers in later levels accessible without detours taking too much time. For this end, I need to get 40 credits on this level (I can get 20 in next level before reaching the dispenser), which means killing 8 enemies. Of those, 7 can be killed and credit collected without delay. This leaves one more enemy to kill.

The one extra enemy is the turtle walking back and forth in the flow. It costs about 12 frames to get this credit, but it is well worth it.

I finish the level with 10 missiles, which anti-carryovers to 12.

One zombie, acid pool and slime can't be shot without hitting them or slowing down even more, so I hit them. Furthermore, the credit from acid can't be collected without slowing down or going to rescue two hostages first and picking the coin on return. The latter is faster for obvious reasons (even if I need to be really fast to make it), so I do that.

I'm lucky there is place on upper floor with switch that locks into the small jumping enemy, otherwise I would have to take a hit from it, losing some more frames.

Yes, it is faster to go against the current for the small section after the second turtle and after the acid pool, but for return trip on former, flying is faster.

The improvements to this level from the first attempts were very large (as I learned how the game physics works).

• Hostages: 5
  
• Switches: 4
  
• Generators: 0
  
• Length: 45.929s (3219 frames)
  

The reason I need 20 credits upon entry is that there are 4 easily shootable enemies, giving 20 credits total before reaching M dispenser, and I need to buy two missile packs there (total cost 40 credits). After this, I have 20 missiles.

I use 7 missiles, in order to end up with 13, which causes anti-carryover to give me 5 more, starting 1-3 with 18 missiles.

The first enemy drops its credit into a pit, fortunately, there is hostage there I need to rescue, so I'll go there, grabbing the credit mid-air. I need to slow down a bit to grab the credit from that wandering slime enemy. Note that enemy manipulation to make that zombie on same floor not screw up everything by drawing in the missile is really involved.

I shoot the robot and collect its credits as that enemy drops 15 credits instead of the normal 5. I also shoot the acid pool because otherwise I would hit it again on way out. I also shoot the enemy hiding in pipe. I also assassinate the fast-running alien (otherwise I would take numerous hits from it).

Yes, that burst from jetpack when descending to the white switch does save one frame. I also need to burst the jetpack in some places to avoid really nasty hit from zombie or to get through doorway (why these controls have to be so bad?)

I shoot the first zombie when running to exit, because that is the only one I can shoot without getting hit by it.

I can find numerous improvements here, but alas, none of them really work (they give bad pixel alignment causing much time loss later, or monsters get placed into bad places. Oh, and you can't permakill all enemies, only some types can be permakilled.

• Hostages: 12
  
• Switches: 3
  
• Generators: 0
  
• Length: 73.710s (5166 frames)
  

I now have 18 missiles thanks to the anti-carryover, and I will use 11 (to end up with 7, which anti-carryovers to 12).

There are four branches, not connected via anything but the central room. Initially only bottom left and top right branches are available. The switch to unlock right bottom branch is in bottom left branch. The switch to unlock the top left branch is in bottom right branch (and actually, it needs second switch there to unlock the cave the switch to unlock the branch is). All branches except top left have 2 hostages (the top left one has 6). I start from bottom right branch.

I kill the turtle even if I take a hit from it, because otherwise I can't kill the zombie before plowing into it.

Those barrels I blow up are impassable. Furthermore, they can't be hit using missiles, leaving only photon blaster or flamethrower, and destroying them with photon blaster shots is 45 frames faster (far outweighing the 13 or so frames it costs to buy the photon blaster packs). I tried buying three packs but it gave really bad luck here, wiping out all the possible improvement.

And in the section where four paths cross, the hole to squeeze into is incredibly tight and it isn't easy to squeeze there.

It is slightly faster to take the further entrance into pipe than to come out via the same entrance as Harry came in.

Again, here alignment and luck is nasty. I find numerous local improvements that don't work.

• Hostages: 14
  
• Switches: 2
  
• Generators: 0
  
• Length: 55.374s (3881 frames)
  

I have 12 missiles which I use all (since any missiles left over would be useless). The credits carry over, so I don't spend them all.

Here, 12 missiles is more than what is needed, which makes enemy manipulation considerably easier. Indeed, I improved this level 41 frames from the initial version. The only other level where I got anything comparable was 1-1 and that was because I didn't understand the mechanics very well when doing it the first time.

Oh, I have to wait for that one hostage, because entering that area is really really difficult (the only way I have discovered is damage boosting there using those spikes, which takes really precise pixel alignment).

• Hostages: 0
  
• Switches: 0
  
• Generators: 0
  
• Length: 29.735s (2084 frames).
  

This boss has slime-throwing attack (7% damage per hit) and touch (50% damage per hit).

As said before, I only have the flamethrower. This enemy has 984 HP. Also, it seems that randomly the game seems to ignore damage to the boss (even if the boss flashes), due to something intentional code to up difficulty. I manipulate that to happen as little as possible.

There is current that pushes you right. The alien can't shoot if you are hitting it. Strategy is to hit the alien periodically while it is moving to left (keeping distance, a hit does really lots of damage), then fly over it (or use the collision bug), fire it while it moves right, fly over it and repeat until it dies (if one does it right, two left/right movements should be enough to kill it).

On both left-to-right changes, I use the collision bug to phase through the boss with no damage.

Oh, and initially I go inside abusing initial mercy invulnerability, hitting it for some fast damage.

Narration: "Back at Starbase Liberty..."
Diane: "Excellent work, Harry"
Diane: "The sewers are once again safe for rats and turtles."
Harry: "And unwanted pet crocodiles!"
(Diane smiles)
Diane: "From the information we gathered from the rescued hostages,"
Diane: "it seems that the Alien infestation is worse than we thought."
Diane: "They are holding captives in the Big Corp factory,"
Diane: "and they plan to turn them into space zombies."
Diane: "Harry, we want you to rescue them!"
Harry: "What, the zombies?"
Diane: "No Harry."
Diane: "The hostages."
Diane: "You toast the zombies!"
Harry: "No problem, I'm all gased up and ready to go."
Diane: "Be careful Harry."
Diane: "Our scanners have detected a giant mutated construction worker guarding the fifth floor of the Factory."
Diane: "He could be dangerous."
Harry. "Diane, I live for danger."

• Hostages: 2
  
• Switches: 5
  
• Generators: 6
  
• Length: 42.376s (2970 frames)
  

Harry doesn't have any weapons aside of the (useless) flamethrower for some reason. But nevertheless I have 110 credits from the last mission. First thing, I go to weapon dispenser to buy some weapons.

Now, this level has six power generators, which you must destroy. Normally these generators take seconds to destroy, which is obviously something I can't afford unless I have no choice. Fortunately, thermo grenades and micro nukes can destroy such generator in single hit. There's dispensers for both on this level, thermo grenades being nearer.

Thermo grenades also have advantage coming in packs of six and being cheaper than micro nukes (which I would need to spend pretty much all credits to get enough to even destroy the generators), so I get to actually use them against enemies too.

Unfortunately, thermo grenades don't explode on contact with generators, making it very difficult to destroy the generators quickly with thermo grenades. Fortunately, this is a TAS, so I can aim very carefully (sometimes having one frame window to throw a grenade).

Then after getting grenades, I head to orange switch and flip it, then heading to hidden zone with backup(!) generator and switch to get to place with the two hostages. Generator is in bottom of the shaft. I don't go there, I just throw a grenade there to destroy the generator, go flip the switch and return. I destroy the cyberzombie so I don't plow into it on the way back. Then I head to basement with 4 power generators.

The zombie kills are there in order to be able to correctly throw the grenades to destroy the generators. I don't destroy the third generator on way to switch (the reason being the barrel blocking the path; no exploding that barrel won't take out the generator). Barrels block the path to the switch, I take those out with flamethrower and flip the switch. On the way back, I throw a grenade to destroy the third generator and proceed forward. I take those two zombies with a grenade (otherwise impact to third zombie would kill me). Then I head to rescue the hostages.

After rescuing the hostages, I go to flip blue switch. Then throwing two grenades to destroy the final generator. The first throw is a decoy, otherwise flying enemy will plow into the grenade, preventing the grenade from destroying the generator. The second grenade actually destroys the generator (the double flash is from these grenades exploding).

Then I head to yellow switch, which is now accessible. I again destroy cyberzombie and flip the switch. Then I proceed to exit. There are three reasons why I don't destroy the spiky enemies or third cyberzombie: 1) I can't avoid impact anyway, 2) Impacts take me almost to point of death, the empty life bar looks funky and 3) if I don't blow them, I end level with 13 grenades, which will anti-carryover to 18 (5 free grenades!).

This level has really many paths and tricks, I improved the first run I made by over 6.3 seconds (to about 42.4 seconds).

• Hostages: 5
  
• Switches: 5
  
• Generators: 0
  
• Length: 92.015s (6449 frames)
  

This level is the longest non-boss level of them all.

I buy OMEGA and immediately detonate it before barrels section to destroy the barrels. This saves over a second for 20 credits.

And yes, it is faster to fly over those conveyors running in reverse than to run against those (10 px/gframe vs 8px/gframe). Flying costs some additional time, but if the distance is far enough, it will be faster.

In the end, I "buy" (the price is actually 0 credits) more fuel, because I don't have enough for the rest of the level and it would cost more time to save the fuel than to buy it.

In the end, anti-carryover gives me 4 missiles and a thermo grenade.

Relative to the first attempt, this was 83 frames faster, albeit I have one less missile pack at the end.

• Hostages: 7
  
• Switches: 3
  
• Generators: 0
  
• Length: 52.721s (3695 frames)
  

Nothing too special. I barely dodge the guard robot (which would instakill me). Also, looks like mother alien isn't the only thing with buggy hit detection. I take 0 damage from plowing to those spikes near the spider.

No, going left and up after the yellow switch does not go to anything useful.

In the end, anti-carryover gives mee 4 missiles and 3 thermo grenades.

I had numerious improvement ideas, but none worked because enemies were at stupid positions (unshootable without taking damage or slowing down) or missiles locked into the wrong enemy. So no improvement over the initial attempt.

• Hostages: 8
  
• Switches: 3
  
• Generators: 0
  
• Length: 42.647s (2989 frames)
  

This level is large, but not too long if one knows where to head.

No, entering to that area in the top with one hostage in it via exit in wall does not work. The exit is just not tall enough (too bad, that would save seconds).

When rescuing those two hostages, one has the option rescuing those before the hostage behind blue door, or after it. Rescuing it after is much slower.

And no, one can't enter the room with blue switch and blue door from below, the entrance is not big enough to enter (but it is big enough to leave).

Also, due to level design, it is not possible to use "rescue hostage through door" glitch to rescue the hostage behind orange door. You just can't get close enough (the "lip" above prevents it).

Relative to the first attempt, this was 83 frames faster.

• Hostages: 0
  
• Switches: 0
  
• Generators: 0
  
• Length: 21.631s (1516 frames)
  

This boss has girder-dropping attack (50% damage per hit) and touch (50% damage per hit).

This boss has one real attack, the girder dropping and that attack is very cheap. That attack is barely dodgeable and takes half of your health in single hit. Also, hitting him takes half of your health.

This enemy has 660HP, and has similar problems with damage not taking as Mother Alien.

I always trail him, because time lost in changing sides is more than offset of not having to keep distance when being ahead of him. I also take damage at the end, saving time not having to dodge the attack.

Narration: "Back at Starbase Liberty..."
Diane: "A job well done Harry!"
Diane: "Every last one of the hostages has been rescued."
Diane: "Now that the factory has been cleared of the Alien menace,"
Diane: "we can try and locate their mother ship and blow it to pieces."
Harry: "Sounds good to me!"
Diane: "With the sewers and factory secured, we're now much closer to leading an assault on the Alien ship."
Diane: "However, our scanners indicate that a number of office workers are still trapped within the skyscraper."
Diane: "Before you enter the ship, we'd like you to clear the building of all civilians."
Harry: "Can't we just nuke it?"
Diane: "Harry!"
Diane: "There are innocent people in there!"
Harry: "Oh, my mistake."
Harry: "I thought they were lawyers..."
Diane: "Space Station Liberty has been retasked over Big Corp, so we can teleport you safely inside."
Harry: "Well, I'm ready when you are!"
Diane: "A word of warning though."
Diane: "The aliens have a Sentry Droid in place on the fifth level of the building." (with image of said droid, with text "mission 1"(sic).).
Diane: "Here are the last images we received from a SPY-CAM that we sent earlier."
(picture of the droid, with text "SENTRY DROID THX 1138". "LAST PICTURE FROM SPY-CAM."
Harry: "He sure is mean looking!"
Diane: "It could prove to be quite a challenge."
Harry: "I hear you loud and clear Diane."
Harry: "I keep an eye out for the big metal dude..."
Harry: "Now, let's get this show on the road!"

• Hostages: 8
  
• Switches: 8
  
• Generators: 0
  
• Length: 49.596s (3476 frames)
  

This level is very tall and uses a lot of fuel. Otherwise not much happening. I buy 5 packs of missiles (this episode uses LOT of missiles).

Finish with 27 missiles -> start next level with 30.

From the first attempt, I improved by 119 frames.

• Hostages: 5
  
• Switches: 5
  
• Generators: 0
  
• Length: 58.599s (4107 frames)
  

Nothing too special, apart from not one but two switches being in hidden rooms.

From the first attempt, I improved by about 10 frames (really 20, but I didn't buy two packs of missiles, I'll buy those in 3-3).

• Hostages: 9
  
• Switches: 3
  
• Generators: 0
  
• Length: 82.441s (5778 frames)
  

This zone is long and has some back-and-forth (go flip yellow switch and return to get the hostage behind said door).

It is possible to rescue the hostage behind orange door without opening orange doors. But due to positioning of the orange switch (it is right in front of the orange door) this doesn't save time so I won't do it.

The hostage rescue order is also dictated by having enough health to survive as many hits as possible.

I buy 5 more packs of missiles (for total of 10 this mission, for comparion, in last two missions, I bought 7 total). This level if any shows the problems of making missiles lock into right targets and to reach the targets in time.

Finishing this level with 13 missiles means I start the next level with 18 (anti-carryover).

Relative to the first attempt, the second attempt improved the level by 16 frames, but unfortunately this for some reason causes HORRIBLE luck in next zone (I can't even match testrun time including improvements to 3-3, trying to hex it desyncs). For this reason, I intentionally lose 5 frames, for 11 frames of improvement.

• Hostages: 7
  
• Switches: 4
  
• Generators: 0
  
• Length: 57.557s (4034 frames)
  

As said, improvement attempts hit horrible luck. In the end, I was able to save 11 frames.

No, you don't need to open the green doors.

Finished this level with 250 credits for starting mission 4 with (and I need lots of credits as missile dispenser is quite far from initial position in 4-1).

• Hostages: 0
  
• Switches: 0
  
• Generators: 0
  
• Length: 20.589s (1443 frames)
  

This boss has blaster attack (7% damage per hit, but often multiple are fired in rapid succession), ground slamming attack (5% damage if Harry is on ground when attack actually occurs) and touch (50% damage per hit). Initial HP is 472.

Again, the problem of hits doing no damage appears. I also need to manipulate the AI a lot (it is invulernable during those attack animations, but in the other hand, you can phase it with no damage).

Narration: "Back at Starbase Liberty..."
Diane: "Congratulations Harry!"
Diane: "Big Corp has been saved from evil Alien intent."
Diane: "Now the workers can return to work..."
Diane: "Cleaning their mobile phones and overcharging the clients."
(Diane smiles)
Harry: "Not a problem. All in a day's work."
Thanks to your great work in Big Corp Harry, we've pinpointed the Alien Ship's entrance."
Harry: "Groovy! Now I can go home and relax."
Diane: "Um, well, we still need you Harry."
Diane: "Unfortunately, our scanner can't penetrate the ship's hull,"
Diane: "so we want you to go in and rescue any remaining hostages."
Harry: "Rescue more hostages? Piece of cake!"
Harry: "I'll be on my way then."
Diane: "Oh, there's one more thing Harry."
Diane: "We really like it if you could locate the Alien leader and put an end to hist regin of terror." (with picture of something looking like Elvis swinging microphone).
Harry: "Sheesh! I better be getting overtime for this!"
Harry: "Okay, I'll give it a shot."
Diane: "Thanks Harry."
Diane: "The entiere free world will be in your debt."

• Hostages: 10
  
• Switches: 2
  
• Generators: 0
  
• Length: 51.008s (3575 frames)
  

The only weapon dispensers on the path are OMEGA and Missile. Now, missiles are useful. But unfortunately, they are very late in the level. OMEGA is early enough, but unfortunately OMEGA is very expensive. I buy 5 of these devices (100 credits!) and use them on my way.

Due to timing, it is only worth to use OMEGA if I would die otherwise or if it kills multiple enemies I would otherwise plow into at once. There are exactly 5 of those places.

It is slightly faster to go to upper branch with hostage than to lower branch first.

I jetpack bit longer than what is needed while chasing that fireball in order to avoid hitting the fireball (it would do far too much damage, even if it wouldn't kill Harry outright).

In the end, 23 frame improvement from the first attempt.

• Hostages: 11
  
• Switches: 4
  
• Generators: 0
  
• Length: 62.010s (4346 frames)
  

This level is relatively long (minute+) and contains some back and forth (like the one with cyan switch). And there are two paths from cyan door (to save the 3 hostages) to orange switch. The upper path (which I take) is slightly faster.

Relative to first attempt, I saved 38 frames.

• Hostages: 9
  
• Switches: 2
  
• Generators: 1
  
• Length: 60.097s (4212 frames)
  

From blue switch to the hostage there are two ways. The lengths are almost equivalent, but going through the right path seems to be few frames faster.

The fastest way to take out the generator is to buy some grenades and throw one from the corridor and then turn back.

When rescuing the block of 6 hostages, it is faster to drop down and the fly up instead of doing the opposite (the time diffrence is about 29 frames).

In the end, second attempt was 31 frames faster than the first one.

• Hostages: 10
  
• Switches: 3
  
• Generators: 0
  
• Length: 69.215s (4851 frames)
  

It is possible to go two ways after leaving the area locked by the green door. Left or Right. Going right is faster.

Nope, in that second structure, it is not possible to return from the bottom to the green door without taking detour (the tunnels between are just too narrow to fly into). The same applies to the middle level.

Also, the final structure has passages too narrow to fly, so one must detour a bit (I need to go rescue hostage there anyway).

From the first attempt, I improved 50 frames.

• Hostages: 0
  
• Switches: 0
  
• Generators: 0
  
• Length: 36.595s (2565 frames).
  

They captured Elvis and made him a zombie? Or resurrected him as a zombie? He throws microphones at you (25% damage on hit) and tries to squish you (50% damage on hit). Also, if he hits you with swinging microphone, that does 75% damage(!. Initial HP is 1313.

No, that star blinking the boss has is not invincibility, nor is it connected to that "does not take damage" problem. It depicts the gems the Leader has in its clothes. So pick correct even/odd phase and have at it, avoiding physical contact.

It seems that when the leader is swinging the microphone, its hitbox is screwy (basically, the hitbox is the microphone).

In the end, it is fastest to just take the desperation attack. I have to run right a bit or the attack would kill me.

Narration: "Back at Starbase Liberty..."
Diana: "You did it Harry!"
(Diana smiles)
Diana: "Once again the world is nicer, rounder place to live!"
Diana: "All thanks to you!"
(Diana smiles)
Harry: "It was nothing Diane..."
Harry: "Nothing that any red blooded American with balls of steel wouldn't have done."
Harry: "Well, I'm outta here!"
Diane: "Where are you going Harry?"
Harry: "Somewhere..."
Harry: "Anywhere..."
Harry: "I dunno..."
Harry: "I'm just wild eyed loner at the gates of oblivion."
Harry: "!"
Diane: "Oh Harry, you are the best."
(Diane smiles)