When the granddaddy of FPS tweets, we listen. For those unaware, that's John Carmack -- you know, the guy behind games like Doom, Quake and Rage -- confirming that Doom 3's engine, id Tech 4, is all bundled up for its open-source release, only awaiting clearance from legal. To be verbose, that doesn't mean you'll be getting down with a gratis copy of Doom, but rather with the powerhouse that powers it, a veritable boon to game developers and tinkerers, alike. The release is par for the course for the company, as id Software's been routinely open-sourcing its older engines for as long as we can remember. We'll keep an eye out for when it drops, but while you wait, feel free to read an interview with the visionary himself.