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.
Finish Chapter 3.
Try jumping over a Deadly Electrified Maintenance Tile... and fail horribly.
Simply walk onto the Deadly Electrified Maintenance tile in Chamber 3-1.
Grill a WorkerDroid on a Deadly Electrified Maintenance Tile.
Finish Chapter 2.
Try painting a brown WokerDroid and realize how pointless that was.
Mix a color. It's not that hard, really.
Get killed by a WorkerDroid.
Finish Chapter 1.
Open a door by activating a trigger.
Fire 100 shots.
Shoot a WorkerDroid.
Try jumping... and fail.
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.
Rescue the WorkerDroid in Chamber 5-2.