A Microsoft patent published in September 2012 describes an "immersive display experience" which outputs an image to a primary display (think your TV) and also "outputs a peripheral image to an environmental display for projection by the environmental display on an environmental surface of a display environment so that the peripheral image appears as an extension of the primary image" [source: Patentdocs]. In other words, a projection device would cast images to either side of your TV, essentially surrounding you with the digital world you're interacting with. Like Microsoft's Kinect, the patent uses a depth camera to track the user and objects in the room.
Video game development engine Unity has partnered with a company called Infinite Z to integrate holographic support into its toolset. Infinite Z's zSpace technology uses head tracking, passive 3-D glasses and infrared technology to create 3-D images right in front of your face, as long as you have a special monitor [source: Co.Design]
Apple's patent for a 3-D system, meanwhile, has less to do with games and more to do with general computer interaction. But once we're moving our hands in 3-D space to carry out virtual functions, it's only a matter of time until games are involved.
But do patents really tell us anything? Companies like Apple and Microsoft patent their research all the time without turning those ideas into real products. Odds are that we'll never see these patents turned into real products, but one day the research that went into them could give us real holographic technology. For now, virtual reality games are much closer to reality.