Here is the full list of all 22 ChromaGun achievements.
Finish Chapter 8.
Finish Chapter 7.
Finish Chapter 6.
Finish Chapter 5.
Finish Chapter 4.
Try jumping... and fail.
Finish Chapter 3.
Simply walk onto the Deadly Electrified Maintenance tile in Chamber 3-1.
Grill a WorkerDroid on a Deadly Electrified Maintenance Tile.
Finish Chapter 2.
Get killed by a WorkerDroid.
Try painting a brown WokerDroid and realize how pointless that was.
Mix a color. It's not that hard, really.
Fire 100 shots.
Finish Chapter 1.
Open a door by activating a trigger.
Shoot a WorkerDroid.
Find the hidden cake we actually have, as opposed to that other game that doesn't have a cake.
Grill 100 WorkerDroids on Deadly Maintenance Tiles.
Solve a chamber in chapter 7 without firing a single shot.
Try jumping over a Deadly Electrified Maintenance Tile... and fail horribly.
Rescue the WorkerDroid in Chamber 5-2.