Hmm, How about a GIANT maze that is customizable, say spawn the maze on the runway on terminal out of the map, make it FFA and at night, falling care packages every 2-3 minutes. There are flag portals, each time you reach a flag you spawn somewhere else. First one to find and pickup a golden gun wins the game (the golden gun could be hidden between care packages or deep inside the maze). You could then make a V2 and have multiple layers/levels.
Or you could make some sort of tetris minigame