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