Here is the full list of all 14 Rock-n-Rogue A Boo Bunny Plague Adventure achievements.
Defeat Andromeda Raid Mech (Bun-209)
Complete level 9 of Hell, Treachery
Complete level 8 of Hell, Fraud
Defeat Dead Jenny
Complete level 7 of Hell, Violence
Complete level 6 of Hell, Heresy
Defeat Puke
Complete level 5 of Hell, Anger
Complete level 4 of Hell, Greed
Defeat Squ1rr3l
Complete level 3 of Hell, Gluttony
Complete level 2 of Hell, Lust
Defeat G-64
Complete level 1 of Hell, Limbo