Here is the full list of all 109 DEVIL GUNS - there are DEMON BULLET HELL ARENA achievements.
Kill the Venom Spider 10 times
Defeat the hell creeper - 2
Encounter the Psycho Skull
Play one hell of a round in TEMPLE
Encounter the Venom Spider
Kill the Lumber Thorn 10 times
Kill the Vinehusk 10 times
Encounter the Lumber Thorn
Kill the giant demon lord two times.
Encounter the Vinehusk
Kill the fat demon boss twice.
Play one hell of a round in WOODS
Defeat the slimy slimes - 11
Defeat the slimy slimes - 2
Defeat the cute devils - 2
Kill the Bloatwasp 50 times
Kill the Bloatwasp 100 times
Kill the Vinehusk 50 times
Kill the Vinehusk 100 times
Kill the Crypt Slave 50 times
Defeat the cute devils - 11
Kill the Crypt Slave 100 times
Kill the Stingviper 50 times
Kill the Stingviper 100 times
Kill the Lumber Thorn 50 times
Kill the Lumber Thorn 100 times
Kill the Psycho Skull 10 times
Kill the Psycho Skull 50 times
Kill the Psycho Skull 100 times
Kill the Venom Spider 50 times
Kill the Venom Spider 100 times
Encounter the Minotaur
Kill the Minotaur 10 times
Kill the Minotaur 50 times
Kill the Minotaur 100 times
Kill the Doom Bat 50 times
Kill the Doom Bat 100 times
Encounter the Hellskull
Kill the Hell Skull 10 times
Kill the Hell Skull 50 times
Kill the Hell Skull 100 times
Encounter the Hell Creeper
Kill the Hell Creeper 10 times
Kill the Hell Creeper 50 times
Kill the Hell Creeper 100 times
Encounter the Devil Eye
Kill the Devil Eye 10 times
Kill the Devil Eye 50 times
Kill the Devil Eye 100 times
Kill the Elder Thorn
Kill the Elder Thorn 2 times
Kill the Elder Thorn 3 times
Kill the Hydra
Kill the Hydra 2 times
Kill the Hydra 3 times
Kill the Arachne Qeen
Kill the Arachne Qeen 2 times
Kill the Arachne Qeen 3 times
Kill the Inferno Behemoth
Kill the Inferno Behemoth 2 times
Kill the Inferno Behemoth 3 times
Play one hell of a round in CRYPT
Play one hell of a round in HELL
Find all Lucky Devil Coins
Ecounter the Phantom
Kill the Phantom 10 times
Kill the Phantom 50 times
Kill the Phantom 100 times
Ecounter the Scorch Maw
Kill the Scorch Maw 10 times
Kill the Scorch Maw 50 times
Kill the Scorch Maw 100 times
Defeat the hell creeper - 11