Here is the full list of all 21 Warpips achievements.
Beat Conquest Mode on any difficulty
Win the campaign on General difficulty
Beat the third island in the campaign
Beat the second island in the campaign
Marines fire 1500 grenades
Complete Endless Mode with at least 150k points
Complete Endless Mode with at least 50k points
Complete Endless Mode with at least 100k points
Spawn 200 Vehicles
Spawn 2000 Infantry
Kill 150 enemies with Missiles
LRV spawns Marines 50 times
Call in 150 Tactician artillery strikes
Capture every territory in the campaign
Beat the first island in the campaign
Sniper kills 100 enemies
Spawn 35 Spec Ops Pips
Shield Pip takes 4000 damage
Mine $5,000 cash from Pumpjacks or Oil Derricks
Kill 500 enemies with Small Turrets
Complete the tutorial.