Here is the full list of all 31 Acquitted achievements.
You beat the first level. Not everyone can.
50 headshots. Not bad kid.
Achieve a 2 headshot spree.
Congratulations king, you completed the warmup. All weapons will now be unlocked by default. The real challenge is about to begin.
Beat level 30.
Beat level 40.
Beat level 50.
Beat level 60.
Beat level 70.
Beat level 80.
Beat level 90.
Beat level 100.
Achieve a 5 headshot spree.
Achieve a 10 headshot spree.
Pick up 100 health packs.
Pick up 100 armored vests.
Drink 100 energy drinks (don't actually do it).
Place 100 barricades.
Get hit by five peepeepoopoo.
Get hit by 50 peepeepoopoos.
Miss a weapon drop (they spawn again, don't worry).
Get hit by a brick.
Remove a tank corpse from the map.
Defeat a landwhale.
Defeat your first Ma'am tank.
Defeat 10 Ma'am tanks.
Defeat 50 braindead while the energy drink is still in effect.
Chop off 10 heads.
Defeat 100 knife-wielding enemies.
Beat a level without getting hurt.
Beat levels 1 to 20 without getting hurt.