Bethesda have detailed their 20th anniversary celebrations for the game Wolfenstein 3D, a title that was instrumental in the creation of the entire first-person shooter genre.
To start with, they've released a free to play web version of the game, which you can play from any modern browser here.
Additionally, the new Bethesda Podcast, which you can watch below, features John Carmack (the technical director of id Software) as he discusses the creation and development of the title:
Finally, Wolfenstein 3D Classic Platinum - the iOS version of the 20 year old classic - is available for free for a limited time, unless you live in New Zealand. For tax reasons, id Software games on the App Store are not available to Kiwis, including Wolfenstein 3D Classic Premium (the demo, however, is available).