Here is the full list of all 24 Metal Soldiers 2 achievements.
Kill 1000 non-vehicle enemies
Destroy 100 enemy vehicles
Kill 250 low rank soldiers
Kill 200 mines
Kill 150 machete soldiers
Kill 200 sky divers
Kill 150 chainsaw enemies
Kill 250 enemies using the tank
Kill 250 enemies using the helicopter
Kill 250 enemies using the mech
Kill 70 enemies using boxes
Get into a vehicle 25 times (only once per vehicle)
Kill at least 1 enemy from each type
Finish a mission without getting shoted
Get 1 minute in your endless mode clock
Get 2 minutes in your endless mode clock
Get 3 minutes in your endless mode clock
Get 5 minutes in your endless mode clock
Get 10000 points in an endless run
Get 30000 points in an endless run
Kill 30 enemies in the sky
Kill 50 enemies using the knife
Get 100 power-ups
Get to the choppa!