Here is the full list of all 27 BUTCHER achievements.
Upload your level pack to the Workshop.
Complete the game in 1 hour on at least HARD difficulty.
Complete the game in 45 minutes on at least HARD difficulty.
Complete the game on "Harder" difficulty.
Complete the game in 1.5 hour on at least HARD difficulty.
Find all skulls.
Find 30 skulls.
Unlock new difficulty mode.
Complete the game on "The Hardest" difficulty.
Find 20 skulls.
Kill 10 enemies with a single railgun bullet.
Die 200 times in total.
Maul 200 enemies to death with a sawspider.
Impale 50 enemies on hook by kicking them.
Impale 25 enemies on hook by kicking them.
Complete the game on "Hard" difficulty.
Beat The Last City.
Repeat a single level 10 times.
Beat Volcano Research Station.
Find 10 skulls.
Beat Jungle Outpost.
Kill 1000 enemies.
Beat Old Military Base.
Make 200 enemies die horribly by burning alive.
Beat Ironworks Facility.