The source code (and original assets) to many video games from as late as the 90s has been lost. The publishing company often deleted it after the game shipped, thinking it just took up space. This is one reason why, for example, there hasn't been a substantive remaster of Final Fantasy VII.
These two guys* were crazy productive in the 2 months they worked. Just the level of commenting shows how much thought they were able to give it during that span.
https://github.com/microsoft/BASIC-M6502
Celebrate 50 years of Microsoft with the company's original Source code
https://www.gatesnotes.com/microsoft-original-source-code
(Discussion: https://news.ycombinator.com/item?id=43575884)
hah I've never seen that before but reminds me to roguelike games.
"permadeath coding" would be actually fun. IF compiler error THEN erase code repository or something like this
https://www.folklore.org/MacBasic.html
Also, it sounds like you described Vigil: https://github.com/munificent/vigil
* plus the math package guy
I.e., has anyone OCR'd the listing and fed it into an emulator yet?