Here is the full list of all 50 Geometric Sniper - there are Z achievements.
COMPLETE 2 REWARD MISSIONS
COMPLETE THE 3rd MISSION
COMPLETE THE 2nd MISSION
COMPLETE THE 1st MISSION
COMPLETE THE 4TH MISSION
COMPLETE THE 5TH MISSION
COMPLETE THE 6TH MISSION
COMPLETE THE 7TH MISSION
COMPLETE THE 8TH MISSION
COMPLETE THE 2nd SURVIVE
COMPLETE THE 6TH SURVIVE
COMPLETE THE 10TH SURVIVE
UNLOCK ALL SURVIVE MAPS
COMPLETE THE 1st RUNAWAY
COMPLETE THE 2nd RUNAWAY
COMPLETE THE 3rd RUNAWAY
COMPLETE THE 4TH RUNAWAY
COMPLETE THE 5th RUNAWAY
COMPLETE THE 6th RUNAWAY
COMPLETE 4 REWARD MISSIONS
COMPLETE 6 REWARD MISSIONS
COMPLETE 8 REWARD MISSIONS
COMPLETE 10 REWARD MISSIONS
KILL 1000 ZOMBIES
RESCUE 100 SURVIVORS
SPEND 80K SUPPLIES
12 HOURS OF PLAY TIME
COMPLETE THE PET
COMPLETE THE 9th MISSION
COMPLETE THE 10th MISSION
COMPLETE THE 11th MISSION
COMPLETE THE 12th MISSION
COMPLETE THE 13th MISSION
COMPLETE THE 14th MISSION
COMPLETE THE 15th MISSION
COMPLETE ALL MISSION IN ADVENTURE
UNLOCK THE 4TH SURVIVE MAP
COMPLETE THE 7th MISSION
COMPLETE THE 8th MISSION
COMPLETE ALL MISSION IN RONAWAY ZOMBIE
SAVE AT LEAST 3 SURVIVOR IN EACH STAGE (ADVENTURE MODE)
COLLECT ALL ACHIEVEMENTS
COMPLETE 12 REWARD MISSIONS
COMPLETE 14 REWARD MISSIONS
Infect 100 people in Runaway Mode
Kill 3 zombies with one sniper shot