Here is the full list of all 20 Thunder Wolves achievements.
Kill 100 enemy helicopters.
Complete at least one mission with each helicopter.
Complete all levels at least on normal difficulty.
Kill 10 vehicles by smashing into them.
Kill a boss/miniboss by smashing into it.
Collect all 25 crates hidden in various locations.
Find and eliminate Pedro in all locations.
Destroy your chopper with your own guided rocket.
Locate and winch up the Lost Ark.
Purge the island of the dead.
Complete a (non-tutorial) mission in 8 minutes or less.
Score at least 500,000 points in a single mission.
Destroy 1,000 buildings.
Complete a (non-tutorial) mission using only rockets.
Complete a (non-tutorial) mission using only the machine gun.
Kill two enemy vehicles with one rocket.
Complete the first main mission objective.
Complete a mission in co-op mode.
Complete the 'Stomp The Snake' mission on expert difficulty level in co-op mode.
Get all stars in all missions.