Think of two or more games that could be combined, but probably shouldn't. Some, like [url=http://www.halolz.com/2011/07/27/bioshaq/]BioShaq[/url] could even be fun.
If you're going to post a game crossover, try and be creative and describe how the game would work.
Now would you buy it?
I know I'd buy [i]Gears of Halo Theft Auto V[/i]