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