Here is the full list of all 25 The Mimic achievements.
Die on the Mimic for the first time.
Be killed by a laser for the first time.
Die 100 times.
Lose your Mimic.
Complete the Game.
Complete the Co-op.
Complete the first reactor level.
Get your first gold medal on any time trial.
Get your first silver on any time trial.
Jump on another players head in co-op.
Get your first bronze on any time trial.