keen

It did not use protected mode https://github.com/keendreams/keen https://fabiensanglard.net/ega/

I did not know the sources of keen game/(s?) were available. I remember reading in "Masters of Doom" about the scrolling technique [0], and how ID tried to use it to create a port of Mario for the PC. Now I can read the code, too :-). [1] 0: https://en.wikipedia.org/wiki/Adaptive_tile_refresh 1: https://github.com/keendreams/keen/blob/4348b4719be87a0b873f...

I have been reading through the Commander Keen source code. https://github.com/keendreams/keen Sprites have precomputed shifted versions so they can be drawn with fewer than 8 pixels alignment. The number of cached sprite versions can be set per sprite, and ranges from 1 to 4, so sprites can never be placed at odd pixels. EGA has hardware scrolling to compensate for the 8 pixel wide bytes, where you set the ”pel panning register” to a value from 0 to 7. For some reason, Keen Dreams ANDs this with 6, removing the last bit. I’am guessing it is to avoid stuttering when the player sprite moves sideways at the same speed as the viewport is scrolling.

Back in 2014 John Hall found the source to some of the old stuff, including Keen 4,5,6 https://games.slashdot.org/story/14/09/17/133228/commander-k... The game was bought by fans, the source was released and Keen Dreams was published on steam. https://github.com/keendreams/keen https://store.steampowered.com/app/356200/Keen_Dreams/ The ownership of the older stuff is quite fragmented.

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

You have to build makeobj first: https://github.com/keendreams/keen/blob/master/static/makeob...

The imperative game logic stuff would be about the same. If this happens, print this and that. If this key is pressed to these 5 things. You can't abstract those steps away. However, video, audio, input handling, and loading resources would be a lot simpler. E.g. take a look at the input manager: https://github.com/keendreams/keen/blob/master/id_in.c You also wouldn't have anything like this: https://github.com/keendreams/keen/blob/master/id_ca.c You'd put some resources in a list and that's all the caching you'd do. You should be able to do a game like this in less than 10k lines of Dart/TS/JS (2D Canvas, Web Audio, Gamepad API). Without using any external libraries or engines, that is. It also would be a lot easier to write, because all of the low level parts are gone.

Carmack's piracy protection was bleeding-edge stuff, back then! https://github.com/keendreams/keen/blob/master/kd_main.c#L39...

https://github.com/keendreams/keen/blob/master/id_us_a.asm#L... > baseRndArray dw 1,1,2,3,5,8,13,21,54,75,129,204 Hah he got the Fibonacci series wrong (it's supposed to be ...13, 21, 34, 55, 89, 144, unless he did this on purpose).

The variables are here, though... https://github.com/keendreams/keen/blob/f477cef79f0893420f47...

Had to press F10 and one of the debug keys (eg. J for Jump cheat) https://github.com/keendreams/keen/blob/f477cef79f0893420f47...

Doesn't really reference mooning, I guess: https://github.com/keendreams/keen/blob/master/kd_keen.c#L15...

http://github.com/keendreams/keen/blob/master/kd_main.c#L279 God, so wish I'd known this at the time.