If you're hanging on to a copy of Gears of War and are looking for something new to do with it then Lance, a new modification for the game, just might be the ticket. You can even find details about how to make your own map for the gametype.
Lance is a TDM experience straight out of the SinglePlayer architecture. The whole gametype has respawns enabled and the action is non-stop, just like a Multiplayer game with some Bots AI. You can chose your team as well as the difficulty level. The spawns are surrounded around the level in unwanted holes so the AI's go inside the actual level and take part of the action. The weapons are randomly given to both the player and AI's, there is 1 chance out of 7 to spawn with a super weapon.