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