Pistols At Dawn
FFA Slayer, 50 points to win. Bonus points on, starting weapon- magnum. Weapons on map set to pistols. Starting 'nades off and shields off. Overshield powerups off. Motion tracker off. Extra Damage optional. Vehicles off.
Best on Ivory Tower.
CS Halo
Assault. Single bomb, first to 4 rounds. One life per round, reset map off. No shields, no motion sensor, human weapons only on map. Start with magnum and no grenades (like how you have to buy these in CS). Extra damage optional but not recommended, also turn off Active Camo and Overshield powerups. Vehicles off.
Best played on Human maps.
Snipe Machine
Team or FFA Slayer. First to 50 kills. Start with Sniper and Beam rifle. Grenades off, all vehicles off, and weapons on map set to Sniping. No powerups, extra damage on, shields off (I hate shields

Best played on Containment, although is possible on Coag and Waterworks. But having played it on Containment with 2 friends, I've come to the conclusion this is where it's at its best.
Randomness
Team or FFA Slayer. Random start weapons, random vehicles (all of them). Basically set everything you can to random (although setting weapons on map to this is not recommended). 50 kills to win, shields optional. Bonus points on.
Playable on any map.
REAL war.
Any team game. CTF, Territories, Oddball, whatever.
No shields, extra damage optional but not recommended unless you're really good (or suicidal). All powerups off. Starting weapon set to Battle Rifle and magnum, weapons on map set to Human. 1 life per round, round length and score set according to gametype. Motion sensor off.
Best played on large team maps (I'm looking at you, Containment) and introduces the tense atmosphere of a real war where you won't be able to just respawn after you die. This gametype promotes stealth to survive longer, and requires good teamwork and coordination to win.
Add your best gametypes here
