Hah, the bad experience one is more about how far you can get before you die. Perhaps have a second class of modes that are along those lines, only they'd be Demons, like Demon of Bad Experience.
I like the explosions idea, maybe add explosions to all projectiles (bullets become as imp fireballs)
continuing on the demon idea:
Demon of Distraction: randomly, the game advances 1-3 turns ahead, while you stand around comatose
Demon of Travel: randomly, you teleport somewhere on the level
Demon of Annihilation: all shots are one hit kills for you and demons alike (hahah yeah right!)