Here is the full list of all 14 Three Dead Zed achievements.
You found a secret message.
Your escape begins here. (Start office 1)
Yep - That's a cat with a tinfoil hat.
Found a secret room. Shhh.
Found all secret messages
Took 5 dangerous paths out.
Beat the game. Unlocked Challenge levels.
Well...not quite yet, but you're looking good!
Kill 100 Civilians
Found all Potato Boys.
Died 100 times
Died less than 30 times completing the game
Beat the game under an hour
Complete challenge stages in under 45 minutes