Y'know, with the MGS-related stuff in AS:Brotherhood, I'm in the mood for a crossover of MGS, Assassin's Creed, the older Splinter Cell games, and Hitman. When Abstergo discover the remains of the Patroits AI systems, they hire mercenaries to retrieve it. The Assassins hire the guys listed. Outgunned, outmanned and outmatched, this ragtag group of heroes must come together must beat the enemy in a way that could only be described as epic.
Also, the Smash Bros characters in Marvel vs Capcom. DC would be included so that the comic characters are not outnumbered by game characters, thus making it Marvel vs Capcom vs Nintendo vs DC. Who honestly cares about the story for this game? In fact, I'd have the announcer in an opening cutscene say "Why are these people fighting, you ask? WHO CARES?! Batman is karate-chopping Frank West while Captain America throws his sheild at Link!" There would also be two games, one in Marvel vs Capcom style, and one in Smash Bros style!