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