The art is absolutely amazing. As someone who is really bad at it, I completely envy you :D
As for the game, although I understand that, in hell, getting the enemies being killed by the traps set by the devil make somewhat sense, from a player's perspective, I would say it would be better if only the player was able to kill the devil troops! I would also make sure to add different bullets for the trap, player and enemies that shoot :D Everything else, great!
As for the gambling, I loved the UI and everything and the trigger works similar to brotato (time-based). Would just make it more transparent to still be able to see the game in the back, as it seems quite forced on to my screen!