It was pure serendipity, according to Treyarch. Forget how the studio is essentially delivering at the start of a wave of stereoscopic titles, and neatly beating Sony's mega-hyped 3D support for Killzone 3 to release with its own all-conquering franchise; it was all just a lucky coincidence from some of Treyarch's R&D developers who decided to play around with 3D rendering. Only, they say, it looked good. Really good. Better than any other 3D shooter in development, they say. So it's now in the game.
For all the considerable amounts of flak Treyarch gets, it's refreshing to see a studio unafraid to muck about with ideas and include their unlikely favourites in final code. World at War's Zombies went from a source of ridicule to a much-loved favourite overnight, and Black Ops' promising newbie-friendly Combat Training was initially developed as a tool to test weapon balancing. 3D isn't going to upset the franchise's tone in the same fashion as turning Nazis into the walking dead, but it's another feature born out of Treyarch's same desire to tinker and modify.
So, here are the technical details: the game is stereoscopic 3D out of the box for 360 and PS3, with the PC version running on NVIDIA 3D. You'll need the required assortment of a 3D television, fancy glasses and bottomless pockets, but if you've somehow got that all in place then you can easily flick to stereoscopic 3D from the game's options screen.
The 3D trickery comes with all the similar trappings of other 3D technology – a slightly odd feeling in your eyes as you accustom yourself to the screen, for instance. But once you're all settled then it's easy to stare at the display for a protracted period of time without any discomfort; that's key to the implementation, too, seeing as people (and by people, I especially mean me) tend to binge on multiplayer for hours on end.
To support the technical demands of rendering fancy 3D, the game [on consoles] runs at a slightly lower resolution than the 2D implementation. I also observed a noticeable drop in frame rate from Call of Duty's trademark silky smooth 60, though Treyarch assured me the game had been 'optimised' to run in 3D.
The effect works better in certain areas than others, of course. Treyarch showed the opening of the game's third mission, Numbers, which starts with you interrogating a soon-to-be informant in Kowloon City. The money shot is right there at the opening, as you bang the poor guy's head into a window pane. Only you'll look straight past that, instead focusing on the world outside the window; the depth of field is particularly striking here, and the 3D effect looks incredible. I think it's the first time I've ever felt like I'm properly looking out of a virtual window.
The scene quickly moves on to your character breaking said window, picking up a shard of glass and depositing it into the man's mouth before punching him in the face a few times. The victim is left spitting out bits of bloodied glass. For the record, it still looks pretty grim without the 3D glasses.