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