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