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