A list of all currently known glitches and bugs in the Test Subject series. Due to all the games in the series sharing similar engines and mechanics, some glitches can be seen in multiple games. Many of the glitches in the series are caused by the behaviour of teleporters or the fact that a wide variety of characters with different mechanics can be played in the same environment.
Note: For the remainder of this page, "Rex209" may be used as a character name to refer to both Blue Rex209 and Professor Rex209 as both characters have almost-identical behaviour and mechanics in their games.
Portal clipping glitches[]
These glitches are caused by the way teleporters behave in the games and allow the player to use them in unintended ways, such as ending up in the wrong end of a portal upon traversing it. Portal clipping glitches are often more difficult to perform than other glitches in the series and require a high precision with the character's movement.
Turnaround clipping[]
Games: All
Characters: All
This glitch allows the player to clip through any vertical portal in the game by using precise walking movement. Unlike many glitches in the game series, turnaround clipping can be performed without a proper setup or knowledge of how the glitch works, by just walking up close to a portal and quickly imputing left and right movement. However, there are ways to make this glitch more consistent.
Whenever the player is standing still they can slightly press both directional arrow keys in quick succession, starting with the one opposite to the way they were facing, to do a short step backwards while keeping their character orientation. Doing that very close to a teleporter while facing away from it can result in the player moving a couple pixels at a time into it, which can eventually lead to the character clipping through without being teleported. The timing for this glitch is precise, but relatively failsafe since the player only has to input short left and right movement keys over and over until they have successfully clipped. It is possible for this glitch to be easier to perform in certain games or situations, and with certain characters.
Portal bumping[]
Games: Test Subject Arena 2
Characters: All
This glitch allows the player to exit a portal the opposite way it was intended to be, and can only be performed with three-block high vertical portals. The player has to jump through a portal while walking in one direction and then change their direction while jumping, which will allow their character to collide with the block on top of the portal, which at a specific angle has a different hitbox from the normal solid blocks. Colliding with a solid block which a portal is connected to pushes the player away from the portal, which allows the player to clip through the portal the wrong way. This glitch is very precise, but if performed correctly, allows the character to end up on the other side of the second portal.
Because of the nature of this glitch, the movement inputs required to perform it differ for all characters, due to their different speeds. It is recommended to use a fast character like the Professor or Orange for this glitch due to their high mobility. Furthermore, the portal-clipping glitch has to be performed differently when using Blue in Rex209 or the Professor in Rex209, as they will try to land on the block on top of the portal, but will be unable to do so because it is connected to the portal.
This glitch can also be performed without the player having to change their direction while in mid-air. The player still has to time their jump very precisely in order to clip with the top of the portal at the right angle. Clipping through the portal this way allows the player to teleport to the other portal facing the wrong way, but still moving in the same direction, essentially making the player enter the second portal and exiting the first one they went into on the other side. Performing this glitch this way is more difficult than when changing directions while in mid-air because the player cannot monitor their angle of approach as much and has to rely on perfect timing, making this version of the glitch much more unreliable.
This glitch cannot work if the portal the player is trying to clip into is embedded in a wall, as the top block of the portal does not have the proper hitbox. The portal has to have a platform or ceiling on top of itself for the collision to properly work.
This glitch also cannot be performed by entering the portal from the left. The player has to enter the portal from the right in order to clip into it at the right angle.
Animation glitches[]
These glitches are all performed by inputting a specific action during a character's animation, which will prevent the action from happening but will still carry some of its effects if the button is held. Inputting an action before a previous animation is over is often known as animation buffering or animation cancelling. This can lead to unexpected results, such as the character performing multiple actions at once.
Super jump[]
Games: Test Subject Blue, Test Subject Green, Test Subject Arena
Characters: Blue, Green
When the player respawns to a checkpoint after being killed, they can hold the up and shoot buttons during their respawning animation, resulting in them rocketing up into the air as soon as they regain the control of their character. The character will be accelerating upwards at a fast rate, which can allow them to traverse the entire level vertically if they don't bump into a ceiling. The player can use the left and right movement keys to slightly adjust their trajectory.
Turnaround sliding[]
Games: All
Characters: All
Whenever a character starts walking towards the opposite direction they were previously facing, a very short turnaround animation will be played. This animation can be paused into a single frame if the player holds both the left and right buttons during it. This means that if the player starts holding one direction and almost immediately starts holding the other direction at the same time, they will start walking while frozen in their turnaround animation. For example, if the player is facing left they can hold the right and then the left button a few frames afterwards, which will make them slide right until either direction is released or they press any other button.
Additional behaviour with Rex209[]
This glitch has different properties with Rex209 due to their unique ability to shoot while walking without slowing down, as well as to recoil back when standing still and shooting. Since they lack a turnaround animation, this glitch will result in them sliding "backwards" as they stay in their standing animation, facing the wrong way. Shooting while sliding will not interrupt the glitch, but instead will slow them down to a halt, where they will be frozen in place. Shooting once more will make them slide in the opposite direction (the one they appear to be facing). Any subsequent shot will make them accelerate, allowing them to travel much faster than their default walking speed. Furthermore, their bullets will be incorrectly fired to the side of their actual sprite, making them able to shoot through walls. If a turnaround slide is performed by Rex209 on a ceiling, they can pick up enough speed to outrun their bullets without getting hit by them. However, as soon as they go through a teleporter or they drop off their platform, they will be hit by their own shots. If they do not hit themselves, they can carry their acceleration into a ground slide until they hit a wall.
Idle walking[]
Games: All
Characters: All except for Rex209
If the player starts holding the jump button while airborne and continues to hold it as the they land on a platform, the character's movement actions will be impaired as long as the jump button is held. The character is unable to crouch, and moving left or right will cause the walking animation to continue playing, even if the character stands idle. The walking animation can be canceled if the player shoots, and crouching only has effect on the player's momentum.
Flickering falling animation[]
Games: Test Subject Arena 2
Characters: All except for Rex209
If the character falls off of a platform without jumping, and the player holds the crouch and shoot buttons simultaneously, the character will act strangely. The character sprite will rapidly switch between frames of its falling and air-shooting animations on every frame until they reach the ground or the buttons are released. If the glitch is performed with Professor, he will have his normal falling animation but will repeatedly play his attack sound without attacking.
Shooting aerial jump[]
Games: Test Subject Arena 2
Characters: All except for Rex209
If the player falls off a platform without jumping, they can press the jump and shoot buttons at any time during their fall to perform a short jump in the air. Since the character ended up in the air without jumping, they can still use their jump if buffered during an attack, resulting in them doing a ground attack quickly followed by a short jump while not being on solid ground. It is possible to start holding the jump button as soon as the character drops from a platform and shoot at any point during the fall to perform the aerial jump.
Shooting aerial jumps are much shorter than usual jumps and only lift the player half a tile upwards, though if performed immediately after leaving a platform they can allow the player to jump up to two and a half tiles. Though these jumps are short, they can be useful by resetting aerial momentum. The height gained from a shooting aerial jump on the edge of a platform can vary from one character to another depending on their speed and firing speed.
When performing shooting aerial jumps, the Professor's melee animation will be canceled by his jump before having an active hitbox, resulting in him not attacking and only jumping.
Tile collision glitches[]
Games: Test Subject Complete, Test Subject Arena 2
Characters: Rex209
These glitches act very similarly and are due to Rex209's ability to walk on the ceiling. They are mainly caused by the bottom hitbox of some platforms being glitched, allowing the player to collide inside the block.
Tile collision behaviour[]
In some areas of the game, it is possible make Rex209 get inside solid level collision, which will confuse the game as to how the character should be interacting with its environment. Since Rex209 is both able to walk on floors and on ceilings, being inside a wall will cause them to latch onto floors and ceilings at the same time, which can allow for vertical travel through levels.
Usually, when Rex209 gets inside a wall or gets in a situation where the game believes they are inside a wall, jumping can either lead to them flipping over as if they latched onto a ceiling or make them drop down by a few tiles. In such a scenario, horizontal movement is impossible most of the time and the player will only be able to go down. Crouching or holding the jump button can sometimes make Rex209 move quicker down. This will often lead to the player either falling off a level, getting stuck or dropping to another part of the level.
Box-clipping[]
Games: Test Subject Arena 2
This glitch can only be performed thanks to a very specific arrangement of boxes in a level. The character has to move near a place where there is a small block on a big block next to a small block. Rex209 can stand onto the small bottom block, directly touching the larger one. If the player jumps while in that position, they will get stuck in the block they are standing on. This puts Rex209 in a tile-collision state, allowing the player to go through the floor by jumping.
Invisible collision[]
Some levels have specific places where invisible collision can be interacted with. Most characters will be able to walk through them normally as if nothing was there, but Rex209 can use them as parts of a wall, triggering tile collision.
Ceiling lamps[]
Games: Test Subject Complete, Test Subject Arena 2
Most of the time, when trying to latch onto a portion of ceiling where there is a lamp, Rex209 will be pushed away and fall back. This can vary based on the side of the lamp the player tries to jump to, or their angle. This will only occur when trying to latch onto a lamp, as they will not impair Rex209's movement if the player is already on the ceiling and passing through them.
TSC: Level 4[]
Games: Test Subject Complete (level 4)
If the player walks over to the food pill capsule, stands in front of it, and jumps, Blue will try to land on the ceiling but will be pushed down to the floor instantly. If the player holds the jump button, blue will stand underneath an invisible platform the same widths as the food pill capsule. Blue can turn around and fire normally.
TSA2: Level 18[]
Games: Test Subject Arena 2 (level 18)
The small alcove in between the two buttons in the bottom of the level has some invisible collision on its leftmost wall. By jumping onto this wall as Rex209, some unintended behaviour may happen such as the player jumping in mid-air. Like with most tile collision, the player can use this collision to fall off the level, or get stuck in the floor. By jumping or falling on to it at specific angles, Rex209 can also be flung upwards, with varying heights.
Loading glitches[]
These glitches are all caused by either pausing the game, restarting a level or respawning after death.
Background Mercenary animation looping/freezing[]
Games: Test Subject Complete, Test Subject Arena 2
If the player pauses the game, the mercenary standing in the background of the test chamber will endlessly repeat its current animation. This can also happen when Blue collects the food pill at the end of a level. This glitch is more prevalent in level 6 of Test Subject Complete, as the Mercenary interacts with the test chamber.
TSC: Level 30 (boss) laser sound[]
Games: Test Subject Complete (level 30)
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During the boss fight, if the player dies or exits to menu while The Machine is using its laser attack, the laser sound will continue playing without interruption. Muting and un-muting in-game sounds will not fix the glitch, and the sound will only stop if the laser is fired once more. Prior to version 1.2[1], this glitch will also occur if the player resets the level while The Machine is firing its laser. | |
TSC: Level 30 (escape) restart[]
Games: Test Subject Complete (level 30)
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After beating the boss in level 30, the player has to escape the base. If the player tries to restart the level by pressing  The level 30 without the player nor the starting door. | |
Miscellaneous[]
Dodge orange enzyme up-close kill[]
Games: Test Subject Complete
If the player is in mid-air close enough to a dodge orange enzyme, the enzyme will not attack them. This is likely because when both the player and the enzyme are on a horizontal platform, the player can never get that close to an enzyme. The dodge orange enzyme may also exhibit the behaviour because it does not have enough time to dodge the bullet, though it is more likely that the enzyme does not see the player as it does not try to kill them.
TSC: Level 10 out of bounds[]
Games: Test Subject Complete (level 10)
The player can get stuck in an unintended area by using the moving teleporters. With the teleporter in its top position, it is possible to go in and out of it in one jump, since there is no solid block above. If the player jumps a second time after getting through, they have a chance of going into the wall. The player will not be able to get out unless they shoot themselves using the two teleporters.
TSC: Level 22 ceiling laser[]
Games: Test Subject Complete (level 22) Characters: Rex209
If the player gets to the third laser of level 22 and gets on the ceiling, dropping down will instantly kill them if they are close enough to the laser generator, even if they are not actually touching the laser itself.
Orange enzyme suicide[]
Games: Test Subject Arena 2
Characters: Orange enzyme
It is possible for the Orange enzyme to kill themselves without requiring any portals. The player has to crouch, shoot forwards and quickly jump backwards, which will cause them to touch their own bullet and kill themselves. This glitch may make controlling Orange more difficult, as the player has to be cautious not to kill themselves by going too fast.
Death during target challenges[]
Games: Test Subject Arena 2
Characters: All
It is possible for a character to kill themselves with their own weapon in single-player mode. If this happens, the timer will continue until the time runs out, despite the character not being on the screen. The easiest way to do this is with Mercenary, or by using the Orange suicide glitch.
Target challenges score of zero[]
Games: Test Subject Arena 2
Characters: All
Destroying a level's final target while the timer reaches zero immediately causes the player to win with a score of zero. This score is not 00.00, but just 0.
Fixed glitches[]
Repeated level reset[]
Games: Test Subject Complete
If the player held down 
to reset the level, a visual glitch would occur. Doctor Nastidious' laboratory will be shown without anything in front of it except for the pause button in the top right corner. Also, the music played its beginning note over and over again until the player released the button. This glitch could occur in any level of the game, regardless of if they were set in Dr Nastidious' lab or not.
As of version 1.2[1], levels reset properly upon pressing the key, but the laboratory background will still appear for one single frame (33ms).
Moving teleporters incorrectly resetting[]
Games: Test Subject Complete
When the player was on a level with moving green teleporters that had been moved from their default position, resetting the level would not have moved the teleporters back to default.
As of version 1.2[1], moving teleporters get properly reset like every other element of a level.
Double character[]
Games: Test Subject Complete
Characters: Rex209
If the player died in a level and had hit the reset button before being fully reconstructed, Rex209 would have stayed alive but the beginning cut-scene of the level would also have played. Blue would have jumped out of his hiding place, while the original Blue could still be controlled by the player. The original Blue would then disappear once the new Blue becomes controllable to the player once the cut-scene is over, and the level officially "starts" over again.
As of version 1.2[1], Rex209 properly disappears when a level is reset, to then reappear in the intended position.
TSC: level 22 invisible steps[]
Games: Test Subject Complete (level 22)
Characters: Rex209
In the beginning of level 22, if the player goes to the left of the tissue box they spawn at, they will find what seems to be a stack of invisible platforms. These can be interacted with like other examples of invisible tile collision glitches in the game. The player is able to go through the floor by using the jump and crouch keys, going further down the level. The Machine is able to shoot the player during the beginning portion of this glitch as because aren't fully covered by the tissue box.
As of version 1.2[1], an invisible wall prevents the player from glitching through the level.
Notes[]
| v • d • eTest Subject series | |
|---|---|
| General | Test Subject Blue • Test Subject Green • Test Subject Complete • Test Subject Arena • Test Subject Arena 2 • Test Subject series • Glitches |
| Locations | Xeno Industries • Doctor Nastidious' base • Test chamber • Test Subject (Bump Battle Royale arena) |
| Characters | Blue • Green • Professor (Quotes) • Doctor Nastidious (Quotes) • Mercenaries • Rex209 (Quotes) • The Machine |
| Enzymes | Orange enzymes • Green enzymes • Blue enzymes • Enzymes (Bump Battle Royale) |
| Enemies | Orange enzymes (Walking • Shield • Dodge • Flying • Throwing • Juggernaut • Cooked • Dropped) Green enzymes (Monkey • Crawling • Sniper • Bouncing • Mimic) |
| Hazards | Orange enzyme bullets • Proton cannons • Mines • Detection proton cannons • Lasers • Enzyme tubes |
| Interactive objects | Proto-Suit • Key cards • Food pills • Teleporters (Green • Orange and blue) • Mirrors • Spawn cylinders • Spawn areas • Buttons (Switch buttons • Deactivation buttons) • Containers |