First shooter to run on two game engines simultaneously

Halo: Combat Evolved Anniversary (343 Industries, 2011) is a high-definition remake of the first Halo game, released to celebrate 10 years of the popular series. The Anniversary game broke the mould by being able to run across two engines at the same time. Players are able to switch – in real-time – between the original Halo visuals and the new HD facelift. The game simultaneously runs a direct port of the original Halo code with a new renderer layered on top.