Here is the full list of all 42 CubeGun achievements.
Upgrade to Level 5
Survive 5 waves in Arena
Survive 20 waves in Arena
Survive 100 waves in Arena
Win 5 battles in Auto mode
Win 50 battles in Auto mode
Win 100 battles in Auto mode
Kill 10 enemies in Multiplay
Kill 50 enemies in Multiplay
Kill 100 enemies in Multiplay
Upgrade to Level 20
Upgrade to Level 40
Collect 6 weapons
Collect 10 weapons
Collect 19 weapons
Unlock Avatar Animation
Multi kill 5 ships in Arena
Multi kill 8 ships in Arena
Multi kill 12 ships in Arena
Multi kill 3 enemies in Multiplay
Multi kill 5 enemies in Multiplay
Multi kill 8 enemies in Multiplay
Win 5 waves in Arena with only melee weapon
Win 20 waves in Arena with only melee weapon
Win 100 waves in Arena with only melee weapon
Win 5 waves in Arena with only Reflector
Win 20 waves in Arena with only Reflector
Win 100 waves in Arena with only Reflector
Win 5 waves in Arena with no defend device
Win 20 waves in Arena with no defend device
Win 100 waves in Arena with no defend device
Win 5 waves in Arena with full health
Win 20 waves in Arena with full health
Win 100 waves in Arena with full health
Win 5 waves in Arena with health<5%
Win 20 waves in Arena with health<5%
Win 100 waves in Arena with health<5%
Combine 4x4 weapon 5 times
Win 5 different map in Arena
Add 5 friends
Add 20 friends
Add 100 friends