Here is the full list of all 47 Titan Attacks achievements.
Perfect Challenge Level 91
Perfect Challenge Level 84
Perfect Challenge Level 70
100 aliens escape capture
Perfect Challenge Level 98
Perfect Challenge Level 77
Perfect Challenge Level 56
Perfect Challenge Level 63
50 aliens escape capture
Perfect Challenge Level 7
Captured 100 live aliens
Perfect Challenge Level 49
Perfect Challenge Level 42
Destroyed 100 saucers
Completed the Titan levels
Everything maxed out
25 aliens escape capture
Guns and addons maxed
Killed 100 parachuting aliens
Added all addons to ship
Used 25 smartbombs
Upgraded addons to maximum rate
Perfect Challenge Level 21
Captured 50 live aliens
Maxed gun bullets
Destroyed 50 saucers
Perfect Challenge Level 14
Maxed gun power
Got the x9 multiplier
10 aliens escape capture
Completed the Saturn levels
Captured 25 live aliens
Killed 50 parachuting aliens
Got 100 skill shots
Completed the Mars levels
Killed 25 parachuting aliens
Perfect Challenge Level 35
Perfect Challenge Level 28
Captured 10 live aliens
Completed the Moon levels
Destroyed 25 saucers
Got 50 skill shots
Completed the Earth Levels
Killed 10 parachuting aliens
Got 25 skill shots
Got 10 skill shots
Destroyed 10 saucers