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