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