Here is the full list of all 12 Nexuiz achievements.
You read the manual
Won your first game online
Max out medium cost mutator
25 headshots
Use 25 Dynamic Mutators in a match.
Killed 3 in a row using melee attacks
Taken bot training
Use a dynamic mutator for the first time
Use a CTF Dynamic Mutator to aid your team!
Kill a member of IllFonic or someone who has already won this trophy
Awarded 50 unique medals
Played a match on every map