This is fantastic. Tangentially, I did not know the source code was lost:

"Please don't ask for the source; if I had it, I'd release it, but I lost it in a crash a long time ago." -Tim Sweeney

https://web.archive.org/web/19991010013339/http://www.epicga...

I find the whole thing interesting, because I remember the shareware versions that I downloaded from my friendly neighborhood BBS offered the source code for a fee; a large fee, if memory serves. I wonder if any of the purchasers of said source code might still have it sitting around on their floppies somewhere.