Here is the full list of all 24 Trigger Time achievements.
Deactivate all 3 scorpion spawners in the canyon
Kill at least 50 enemies with flames
Kill the spider queen
Kill 3 enemies with a single buzzsaw 2 times in a row
Finish a level with accuracy >= 85%
Escape the prison
Finish a level without losing any lives (hearts)
Finish a level with 0 lives left and health left < 25%
Finish a level without taking any damage at all
Kill 300 enemies with barrels, crates or rocks
Don't let core protector boss hit you with his melee attacks even once
Kill the bugs without using the flamethrower in the subway level
Don't let acid worms hit you while you're riding a boat
Find dopefish in the subway level
Get into dangerous places in the subway level
Kill the skull helicopter boss
Don't breath gas in the gas chamber trap
Don't let creatures in the jars get destroyed in the laboratory level
Destroy all the creatures in the jars in the laboratory level
Defeat the buddy boss
Kill professor Nathan and escape the facility
Beat the game on hard difficulty
Beat the game on easy difficulty before beating it on normal or hard
Find the secret level