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