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