Microsoft has filed an interesting patent for a video game "having a plurality of game engines" running concurrently. The patent was filed in December of 2011, right after the launch of Halo: Combat Evolved Anniversary - a game allowing players to switch between the updated visuals and the original Xbox game's graphics on the fly.

The Halo Anniversary example seems to be the best illustration of what this patent is aiming for. Further down, the patent specifically calls out "remakes" of games, where the original graphics are described as "leveraging" player emotions tied to the original experience. "However, this may be lost as modern graphics may cause the gamers to lose that feeling of nostalgia," the patent reads. So having that ability to switch between an original experience and enhanced visuals seems like a good middle ground this patent is trying to lock up.

A trio of 343 Industries employees, including executive producer Daniel Ayoub, are listed in the patent filing.