Hovertank3D

Hovertank and Catacomb, the games between Keen and Wolfenstein, are both open-sourced: https://github.com/FlatRockSoft/Hovertank3D https://github.com/CatacombGames/Catacomb3D I'm the current owner of the Catacomb games, and have been working on improving and porting them in my spare time (not publicly available yet, but will be When It's Done). Fabien's Game Engine Black Book has been an invaluable resource for me. I highly recommend it!

There's enough old Softdisk/id Software code released that you can trace the evolution of this RNG. First, check out Catacomb (1989). I think this is the oldest of Carmack's games for which source code has been released. This game uses a lagged fibonacci generator: https://github.com/FlatRockSoft/Catacomb/blob/master/CATASM.... This makes sense, it's a generator that requires little memory and no expensive operations such as multiplications. You'll probably also find it in Softdisk's Apple II releases. Carmack's first 3D game is Hovertank 3D, released in 1991. The LFG still exists, but now a "table-based RND generator" also appears. This seems to be the first appearance of the "Doom RNG". https://github.com/FlatRockSoft/Hovertank3D/blob/master/IDAS... The LFG is used when setting up the map, while the table-based is used for enemy AI duri