First off, I have to give a shout out to my buddy Sabre, who became afflicted with the RROD last night, while playing with us in Gears. He'll be out for 3 weeks at most, hopefully. I've suggested to him on his blog that he check out some military sci-fi books by John Ringo to pass the time (as an English major, my natural response to situations like this is to tell people to go READ something LOL. Books are awesome, mmmkay?) Sabre is also the one who gave me the idea for this post, so it's kinda funny and sad that it's going up the day after his Xbox dies...
Note: Most of these variants have not yet been tried by yours truly, so I'm not certain how well the game's structure will allow them to work, particularly on the harder waves. However, on waves 1-20 on casual, at the very least, all of these should be playable. I'd love to try some of them out when I can get a group willing to mess around.
Pimp Hands: Players are only allowed to kill enemies with melee attacks (no chainsaws!). The competition is to see who can score the most kills before the party wipes. Recommended for waves 1-10 only, as the health bonus on Locust makes this too hard after that. Remarks about your pimp hand and its awesomeness are encouraged.
Lumberjacks: Similar to Pimp Hands, except enemies can only be killed by Lancer Chainsaw. Other weapons are allowed for Tickers and any enemy that cannot be chainsawed.
Simon Says Horde: One person is designated "Simon" (or whatever you want to call them). Simon is not allowed to kill anything. This person simply designates an enemy type (Ticker, Wretch, etc), and the other players can only kill enemies of that type. Simon must also make sure players are actually killing what they are supposed to. Simon can change enemy types whenever he/she wants. Simon can call out individual enemies (the wretch in the middle, for example) if the number of remaining enemies is 5 or less. The person with the highest score at the first party wipe is the winner.
Leapfrog Horde: Players take turns killing Locust in a repeating order. For example, Thrawn--> Dark --> Silva --> Bishop --> Derek. In this party, I would have to kill an enemy, then Dark, then Silva, and on down the line. Once Derek has killed one, the circle begins with me again. If someone dies, their spot in the circle is cut out. I expect taking turns like this would actually be a tricky challenge, especially in the higher waves of each cycle.
Head-to-Head Horde: Pretty straightforward, since it's essentially in the game already. The person with the highest point score when the party wipes is the winner. Since you're competing for score, feel free to kill steal, and "opt-out" on reviving someone, if it seems advantageous to your score. It may be wise to require the party to clear the first 10 waves before a winner can be declared, so someone doesn't try to deliberately wipe the group and give themselves the win too early.
Hot-Seat Horde: The person on the "Hot Seat" is the ONLY one allowed to kill anything. After a set amount of time passes (be it 30 seconds, a minute, whatever), the hot seat is passed to the next person in line. If someone is downed, their turn is over, and the next person in line can revive them and start their turn, or start when the previous player dies. The player on the hot seat also changes after every wave. Highest score at party wipe is the winner.
Obvoiusly, many of these games are better suited to maps where the majority of the players can bunker up and remove themselves from the most intense combat. River, Fuel Station (from Combustable maps), Day One, and Jacinto come to mide right away, but I'm sure there are others, as well. Enjoy!