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