Metroid One Zone is a ROM hack of Metroid: Zero Mission developed by DuoLa Ayu. The hack was developed in 10 days mainly as a demonstration of the MAGE tool's ability to modify Metroid: Zero Mission, but the developer refined it further into a compact but polished standalone hack. This hack was released on 1 April 2025 where the main joke (I guess, kinda?) was that the Easy mode was designed to troll exactly one person in the Metroid Construction community while the other two difficulties are proper play experiences.

The hack can be found on here at Metroid Construction: https://metroidconstruction.com/hack.php?id=818

I still had the hack fresh in my head and got that drive in me to TAS this game a bit further. Hard mode has a fairly different starting progression compared to Normal mode for both the any% and 100% routes and I felt the Hard 100% routing was mostly straightforward even with the bit of backtracking needed. This also shows off most of what this hack has to offer outside the intentionally jokey Easy mode.

Hard mode requires a game clear save to play. I just used #9642: Darkman425's GBA Metroid One Zone "Normal" in 03:22.70 to generate the save file needed for this submission by simply resetting the game when the credits scrolling on screen with that input file. The SaveRAM is already updated while the credits play out so it's not something that needs to be all that precise but it's definitely some time after the last input of that file.

Hard mode has its own distinctive starting progression compared to Normal. Mainly, Hard mode has a unique area all its own where Charge Beam (needed for Super Missiles), Super Missiles (needed for Hi-Jump Boots), and Hi-Jump Boots (needed for Morph Ball) are mandatory progression items. Also worth noting is that the door in the starting area that goes to the Power Grip room is permanently closed on that side which forces a different route when collecting all of the items on the map.

For the most part the game mechanics for Metroid: Zero Mission are covered by [Subs-List?GameId=195|the submission notes for the game] but there's one thing I didn't find on the site worth noting since my TAS found one use for it. I will also add some of the mechanical changes in this hack as well.

Power Bomb cutscene control

When grabbing an item that brings up the suit menu and laying a power bomb beforehand, the explosion will cause the player to regain control of Samus after clearing the item name text on screen for a small bit of time before the suit menu needs to show up. However, in my testing the time to lay the power bomb outweighed the benefit of regaining control since it mostly caused a time loss of 10-20 frames. The one use I got out of it was in the room with the regular Bomb item since that alleviated the need to take the time morphing into a ball to clear the way out with a bomb and unmorphing.

Item tank upgrade amounts

In the original Metroid: Zero Mission the amount that a given tank upgrade (Energy, Missile, Super Missile, and Power Bomb) is reduced when playing on Hard mode. In this hack the amounts are the same compared to Normal. The maximum amount of super missiles obtainable has also been increased from 2 in the base game to 4 in this hack which is incredibly helpful as Ridley is fought much earlier in Hard mode and Kraid has an HP increase in this hack.

Long beam's replacement

This hack adds the long beam's effect to Samus's normal shots by default. In its place is the Spazer Beam, which adds two extra shots to the sides of the normal shot which can do extra damage. It's not really important for fighting bosses as there's more than enough super missiles to be found to handle bosses. However, the fact that three shots are being shot at different positions allows for some small bits of clever shooting to speed some sections up in various ways.

Magnetic charge beam

The charge beam has an added effect of magnetizing health and ammo drops to Samus while it charges. The movement speed is dependent on how a given hack implements it, which in this case is quite fast and practical. This is pretty helpful for the Ridley fight but otherwise isn't super important as ammo is plentiful.

Ineffective plasma beam

The plasma beam is obtainable much earlier in this hack compared to the base game. However, there are multiple bosses that simply weren't coded to take any damage from charged plasma beam shots since that's not a normal possibility in the base game. For this hack this affects Ridley, Kraid, and the hanging Kiru Giru (the Zero Mission Spore Spawn-like). This hack enables turning off a given suit upgrade for this reason but, again, it's not a problem since plasma isn't available for Hard mode Ridley and the other two bosses are solved with the many super missiles on hand.

Start to Missiles

The start is similar to the Normal run with the Ice Beam first being grabbed. The rippers in this room actually move faster compared to Normal and are at different places so the approach to the top is slightly different. The first energy tank, found in the starting room's ceiling, is obtained on the way to what would normally be crumble blocks in the next room. Instead, Hard mode replaces that with an elevator to the Hard mode exclusive area.

In the first room of the Hard mode zone requires lots of wall jumping. There's a breakable wall on the middle left side of the vertical shaft with a room with vertical crumble block pillars. Wall jumping is required to reach the mandatory missile tank needed to explore more of the Hard mode area.

From a slightly higher Deorem to super missiles

After obtaining the missiles, the upper right doorway back in the vertical shaft is taken. The hidden passages are used since they're faster than navigating past the space pirates. In the room with the black space pirates, the upper left room is entered first to fight Deorem. The very minor change of moving the eye up a block ended up making the one cycle kill impossible for me to get working at all. Ironic since the change to the position otherwise makes the boss easier to fight casually. The Charge Beam is obtained and is also required for the super missiles.

After beating the beamst, the left pit is taken and Samus moves back to the black space pirate room. This time the upper right door is entered. The pillar in this hallway requires a charge shot to move upwards making the Charge Beam required to beat Hard mode. Past the pillar is the mandatory super missile tank needed to go further on. Samus moves back to the vertical shaft of the Hard mode area, traveling through Deorem's room as it's a bit faster than going back around the other way.

Boots and balls galore

Back at the vertical shaft, the Hard mode only save room is entered where there's a breakable block leading to a green door that needs to be entered. There's a shortcut hidden on the left side of the next room that's taken. Once past that room, another Hard mode only elevator is taken to reach the normal Hi-Jump Boots location without morph ball or power grip. There's a morph ball passage on the left but the item there is currently inaccessible.

After getting the boots it's another trip back to the Hard mode vertical shaft, although a space pirate spotting Samus causes the music to bug out until much later in the run. Once back to the vertical shaft the elevator is taken back down to finally pick up the Morph Ball with the assistance of the Hi-Jump boots.

Power of SPACE and screws

The left side of the map is explored next. When Samus returns to the starting area, an incredibly tight spring ball that requires some speed is used to reach the passageway to the hi-jump boots. Rather than use passageway completely the crumble block path downwards is taken to an obscured lower path connecting the starting room and the left side of the map. Taking the left passageway to the far left vertical shaft a hidden path is taken by firing a super missile at the wall to open a secret path. The second energy tank is obtained by timing spring ball jumps across the crumble block games. This avoids needing to come back to this area with the wave beam entirely.

Once the energy tank is obtained an acid bath is taken to activate the rail in the area. The morph ball only rail is taken to the Space Jump, which is probably mandatory for a real time playthrough of the game. Going back out the last item obtained before exiting the left area is the first Power Bomb tank past a section of crumble block platforms. At least one power bomb is required to reach the next part of Hard mode. The hi-jump boots passageway is entered again, this time going through to reach the elevator. The left morph ball path from the top part is taken and the second power bomb tank is obtained with the space jump. After obtaining the tank, the elevator is taken again to return to the starting room and then the main Hard mode elevator. Back in the Hard mode vertical shaft the lower left path is taken. Two power bombs are used to move through and obtain the Screw Attack.

Ridley the gatekeeper

To the right of the screw attack is the Ridley boss fight room. The main thing that's done in this fight is to use the missiles and super missiles at the start of the fight and use charge shots while waiting for super missile drops. This fight has a lot of RNG concerns that I wasn't a fan of. The first RNG problem is getting Ridley to fire the big fireballs as soon as possible. While I didn't get the near immediate fireballs after the initial attack I did manage to get two big fireball attacks shortly after he turned around which I felt was acceptable enough.

The second RNG problem was getting super missile drops, since super missiles have the highest DPS, from the big fireballs which was a more frustrating experience. Samus entered the fight with 4 regular missiles and 2 super missiles which is burned quickly. While I did manage to find the drop rates on some enemies and objects for Metroid: Zero Mission, it was missing the RNG rates for Ridley's big fireballs. While it might have shared the rate with something else I didn't see any notes on that so I kind of had to do a bit of experimenting to get drops. The first set of big fireballs did give 2 super missile drops for 4 extra shots as well as a bunch of regular missile drops. The second set of big fireballs was less kind, where for a lot of it I got just big health drops. I managed get one with the last super missile drop I needed to end the fight quickly with a couple of supplemental regular missile shots to reduce the amount of super missiles needed by 1 more.

Eagle eyed viewers might have noticed one of the charge shots hitting the small fireball rather than Ridley. That's a definite mistake but I was already kind of frustrated with the item drops and all that realistically affected was maybe firing one regular missile. Super missile drops are the actual bottleneck for defeating Ridley fast in Hard mode so if anything a full rework of the fight would be better than fixing a single missed shot.

Gripping with a post-Ridley map

After Ridley is defeated the right room is taken. This room has metroids that always respawn upon entering the room so it's not worth engaging with them. The missile pack in the upper left part of the room is taken and the upper right door is reached with space jump. The metroid is in the way so running on the middle platform isn't an option. Past the metroid room Samus moves down past the crumble blocks into the room with the Spazer Beam. Once that's obtained a crumble block path is taken to reach the room on the left with a missile pack above the left wall that requires firing a missile.

After obtaining the missile back the right door is taken to the room guarded by the twins, who are swiftly shredded to bits with the screw attack. Taking the lower left door leads to the vertical shaft of the central area. The morph ball path is taken first to reach the Power Grip found past the save room. The red door is greyed out on Hard mode so this is the only way to access the Power Grip.

A brief heck run for a suit

After grabbing the power grip, Samus goes back right to the vertical shaft and takes the lower left door there. In that room is a regular missile pack hidden in the ceiling and a super missile at the end of the room. Once those are picked up Samus heads to the lower right vertical shaft door to a water cave. There's a vine that's just low enough to swipe at the morph ball so a charged spazer shot is used to destroy it before traversing the water and taking the right door.

Further right is the hot zone which is fairly dangerous but the combination of space jump, screw attack, and at least one energy tank makes this manageable for 100%. In the big hot open room Samus takes the lower right path to the glass tube. A power bomb is set and Samus is timed to leave and re-enter the room to skip the lengthy glass breaking cutscene, opening up an upper and lower path. The upper path is taken as there's a missile pack on the way to another upgrade. Another power bomb is set so it goes off while the missile pack text is onscreen to essentially have the wait on the explosion go off when the player loses control anyways. This clears a row of blocks to access the upper door to the Gravity Suit. While this hack doesn't automatically give the varia suit with it, this enables free movement throughout lava, water, and mysterious green goo. Convenient for speeding up movement.

Exploring the upper fire zone

After getting the gravity suit, Samus goes back out to the big hot open room to enter the upper right door. A power bomb is placed such that it instantly kills both of the Kiru Giru grubs blocking the other side of the room as well as clearing the blocks in the way of a super missile pack. Once the super missile pack is obtained, Samus goes past the door to get the Bomb (regular) (singular) upgrade but places a power bomb before picking it up. This serves the dual purpose of clearing the exit path from the upgrade as crumble blocks, uh, block the entrance to the bombs and regaining control after clearing the bomb text on the screen to move towards the exit before the armor menu shows up. This is the one case I found where using a power bomb to regain control sooner than intended saved actual time as it avoided the need to place and wait on a regular bomb to clear the way.

After getting the bombs the lower path in the Kiru Giru room through a crumble block. This winding path leads to the Plasma Beam. The orb is opened with a missile and some bit of movement allows Samus to be positioned closer to the door before losing control on the item cutscene. As one of the remaining items in the hot zone requires speed booster, Samus heads out of the hot zone to come back for cleanup later.

Speeding through the sea

Back in the water room with vines earlier the vines are cleared and the super missile pack guarded by them is obtained now. After they're obtained a hidden morph ball tunnel in the water is taken to go deeper into the water zone. In the room below there's a missile pack in the upper water bit with the fish. A beam shot is charged so that it fires when entering morph ball via power grip to reveal the missile tank. A damage boost is done on the fish to the missile tank but a power bomb is used to clear it out while the pickup text is on screen.

The next room on the left has a lower path that needs to be taken. The speed booster is found in the room below. Due to water being present, the gravity suit is needed to speed boost through the water as otherwise building up speed is prohibited there. The speed booster is immediately put to use to set up a ballspark through a passage to the right that has an energy tank right in the path. Ball form is kept until going down a crumble block path into the big room with the hanging Kiru Giru. Space jump and super missiles are used to quickly knock it down from the ceiling. A small note: not touching the ground prevents the boss room music to play here.

Samus gets into position after the floor is broken to start building up speed to the next room. That speed breaks through the left wall of the next room to a power bomb tank that requires the gravity suit to obtain. Taking the upper door after grabbing the power bomb tank is another large room where the gravity suit allows for much faster navigation. A shinespark is stored while Samus moves to the top middle part of the room under a breakable block. This section would normally require multiple ballsparks if the gravity suit wasn't obtained. With the gravity suit the only stop the ballspark needs is the one at the end where an up shinespark is needed to reach the super missile tank. Unmorphing for the shinespark allows Samus to hit the ceiling sooner to regain control compared to staying in ball form for an up ballspark. After the super missile pack is obtained another up shinespark is used to leave the water zone.

Returning to the Hard zone simply to leave

After the up shinespark Samus is in another hallway that requires speed boosting, to the right this time. A well timed spazer beam shot is used to clear enough blocks to reach the right speed and space boosting is used to get across the acid quickly. Through the morph ball tunnel is the Varia Suit which mechanically is redundant but needed for full completion. Samus then moves through the acid, shooting to reveal the missile pack hidden in the room with minimal slowdown. Samus then builds speed going left while shooting to open the door. Space boosting is used to avoid the speed boost block on the ground that would cancel the boost as well as make the travel to the left much quicker. From there it's a matter of once again returning to the starting room and going back through Ridley's room to the main area due to a locked door.

Taking a very hot bath down below

In the metroid room Samus takes a brief dip in the green goop to reach the hidden morph ball path a bit quicker, leading to a missile pack. From there it's a matter of returning back to the broken tube in the hot zone. This time it's time to go down through the area below to a door. In the next room a regular bomb is used to clear a row of blocks to the lower section. A screw attack is positioned such that the farthest bomb block on the lower two rows is cleared by a jump. From there it's a run to the left with carefully placed beam shots to clear blocks without slowing down and going through the door. While continuing the run left to build speed even more beam shots are fired to clear the blocks required to build speed. Once done, a shinespark back right is performed to speed boost back to the previous room, breaking the speed boost block wall guarding a power bomb tank. All of that was done to avoid needing to backtrack with the wave beam. A shinespark is stored just before grabbing the power bomb so it can be used to speed boost back to the left out of the room. A space boost is then used to quickly reach the door to Kraid.

Kraid's a chump with an unneeded item

While it's possible to space jump over Kraid to get the item behind him, going back out of the item room doesn't change the state of the room. This effectively means Kraid is required to exit the room as the door is locked until Samus leaves the room to the left after Kraid dies. Anyways, Kraid has more HP compared to the vanilla game so in theory this fight would take longer. However, the sheer number of super missiles kill Kraid before he even finishes rising.

A speed boost is built while running into Kraid during his death animation. This is used to store a shinespark after collecting the Wave Beam in the next room. As everything that would normally require the wave beam has already been obtained, this makes this a pointless item for this TAS. Anyways, a diagonal shinespark is performed in Kraid's room to reach the exit door quickly. From there an upper missile block is broken and Samus moves back to the room before the hot zone.

Final cleanup

In the room bombs are place to access and use a launcher back upwards. This upwards path also has an energy tank in the middle. From there the upper path in the spazer room is used and the morph ball path to the right is taken. In the next room a power bomb is used to clear out a bomb while Samus moves to the left to clear out some screw attack blocks in the way. A walk to the left and a run to the right is needed to build up a shinespark, which is then used above the crumbling block platforms to access the power bomb tank bu breaking the speed booster block. The shinespark is done next to the block to reduce travel time back down. Once back to the ground Samus builds up another speed boost and a shinespark is stored on the way to the energy tank. Once that's obtained a shinespark to the right is done to cut down some travel time to the upper exit of the room. From there it's just a straight path to the pirate ship for the ending, with input ending mid-jump.

DrD2k9: Claiming for judging.

DrD2k9: Accepting.

despoa: Processing...