A lot of people have learned a lot from id Software’s classics, which are available in open source form all over the Internet. Even the iOS versions of DOOM Classic [$6.99] and Wolfenstein 3D [$1.99] have been floating around available for anyone to take a look at and tinker with if they so choose. If you’re one of those people, you’ll like this bit of news: Bethesda has released the open source code for these two games in their latest iterations. You can download DOOM Classic open source here and Wolfenstein 3D here and check out what went into the big-time updates that hit both games just as Quake-Con kicked off earlier this summer.
As a refresher, both games were turned into Universal support apps complete with Retina Display support. Also, both games saw a UI overhaul, some music tweaks, and other assorted technical brush-ups, including bug fixes.
If you're the developer type, I’d imagine there’s something cool to learn here, or hey, if you’re just starting out, I can’t think of code better than John Carmack’s to take a gander at. Plus, it’s free! Everyone loves free.