Ok let's do the votes! But should we have some deadline for posting challenges? Anyway here's my opinion as for now:
1. Angel of Vampirism
Reason: Vampirism has been always great in many games! Oh yeah Phobos Leecherz! I kind of like idea of not using medpacks.. you can't plan your tactic or save healing items for tight spots so it's a good idea :)
Healing items don't work, but you gain a few hp whenever you kill an enemy.
2. Angel of Shotgun
Reason: We just NEED Shooty challenge!
Starts with standard Shotgun
Can only equip Shotguns/Combats/Double Shotguns
More shells are spawned in lower levels
Perhaps a guaranteed Advanced Combat Shotgun and Double Shotgun at certain level landmarks
3. Angel of Rocketry
Reason: Hell yeah, why would we need anything else than our precious RL?
In this challenge only you're using RL, monsters are behaving normal.. maybe something like more maze levels or sth should be added? Ah, and you start with advanced RL [these are my ideas, but I'm for basic idea of using only RL]
4.Angel of Meditation
Reason: Feats like getting more XP at expense of health are good :)
Pros: You gain 150 % of XP, you sense monsters, powerups and levers
Cons: Your HP equals 40 and can't be increased by Ironman, powerups still work though. [I don't know if I can vote on my own idea, but I would like to see some challenge with experience bonus, it's always attractive :)
5. Angel of Carnage
Reason: Just like any specific weapon type - it just should be in the game.
You start with a chaingun, and cant't unwield it. (easy challenge).
Yeah, I know my explaintations are kind of lame... I just feel that these challenges would be fun, interesting and sometimes it comes from thought that I think many of us had, like 'wtf why there's no shooty challenge, it's so obvious omg?', so I'm voting on these :)