The shooter that started it all, Wolfenstein 3D, is now available to try in your browser, or via Facebook. It's been 20 years since its release, and Bethesda has decided to celebrate, so hit your source of choice and play away. Just be warned there's none of that WASD fanciness here.
If you're more a mobile person, Wolfenstein 3D Classic Platinum is free on all mobile Apple devices for a limited time starting now. Head here for the download.
To top it all off we have a commentary below with John Carmack where he discusses the game's development, so of course hit that up if you're id obsessive or just curious.