One of the engineers at DICE working on the Frostbite 2 engine has said that by 2013, some of the games running the engine will require a 64bit operating system. He described it as a "great opportunity" for those still running 32bit, to upgrade to Windows 8.
Despite the option of the 64bit OS being around for quite some time already, a lot of PC gamers have yet to upgrade in that direction. In its early days it was plagued with missing drivers and difficulties with hardware, but these days however, the experience is essentially identical to that of x86 counterparts.
While not many gamers may have adopted the operating system, they're almost universally using the hardware already. 64bit CPUs have been around since the early 2000s, perhaps AMD's 64 chips being some of the most well known, though the numbers didn't really begin to add up until Intel's Core 2 Duo became available.
Some of the games expected to make the jump to require 64bit compliance include: Mirrors Edge 2, Command and Conquer Generals 2, perhaps Dead Space 3 and a potential Battlefield 4 as well.
The person behind the initial attention grabbing tweet, Mr Andersson (does he want his phone call?) has been answering queries from gamers since making the post, so if there's anything you want to ask him, hit him up on Twitter.