Here is the full list of all 30 Paint the Town Red achievements.
Defeat The End
Reach Fire & Blood I
Destroy the Jerk
Defeat the Trickster
Reach The Construct
Capture the Pursuer
Defeat the Aberration
Complete 5 Arena challenges
Complete the Prison in Challenge mode in under 2:30 minutes
Complete the Saloon in Challenge mode in under 3:30 minutes
Complete the Biker Bar in Challenge mode in under 3:30
Complete Arena Challenge 1 in under 9:30 minutes
Reach Islands I
Upgrade one of the Beneath classes
Defeat the Necromancer
Reach Ruin I
Complete 3 Arena challenges
Reach Crystal Caverns I
Defeat a Shard Lord
Unlock a permanent upgrade in Beneath
Complete an Arena challenge
Complete the Western Saloon in Challenge mode
Complete the Prison in Challenge mode
Rescue the Apostate
Die for the first time in Beneath
Enter Beneath for the first time
Complete the Pirate Cove in Challenge mode
Complete the Disco in Challenge mode
Complete the Biker Bar in Challenge mode
Complete a Scenario level without modifiers