Here is the full list of all 21 GARAGE: Bad Trip achievements.
Beat the game
Kill Demikhovsky
Unlock a combination lock
Pick up soap in the shower room
Kill Dreadnought
Ride the train
Find a condom
Kill the centipede
Open the shelf in the desk
Smash 15 vending machines
Find a secret passage
Take "heavenly" pills
Score a goal with your head
Kill your first cadaver
Watch a TV show
Find all the parts of Demikhovsky's diary
Dispose of the old boss
Complete the Labyrinth Challenge
Complete the Axe-man Challenge
Complete the Skirmish Challenge
Complete the Arena Challenge