Exploit the Hellhound's greatest weakness

Complete Ghost Town (E3M1) without any Innocents getting killed

Complete The Way of All Flesh

Complete Even Death May Die

Complete Farewell to Arms

Complete Dead Reckoning

Complete Cryptic Passage

Complete Post Mortem

Kill a Choking Hand

Kill 100 Cultists

Find the secret level in The Way of All Flesh

Find the secret level in Even Death May Die

Find the secret level in Farewell to Arms

Find the secret level in Dead Reckoning

Find the secret level in Cryptic Passage

Find the secret level in Post Mortem

Complete The Haunting (E2M5) in under 40 seconds

Defeat the 3 Beasts of Beauty and the Beast (E6M8) in under 3 minutes on Well Done difficulty or above

Kill yourself 10 times in single-player

Find a super secret