I acquired (with help) a killer audio cassette digitizing rig, and then IMMEDIATELY had to spend over 2 months digitizing 90+ cassettes from the 1999 Game Developers Conference (via a slow-and-steady workflow that got the job done without being too disruptive to any other work I was doing).

So, here we are, it's done. Go enjoy 70+ hours of presentations about all aspects of game making and producing, in 1999.

https://archive.org/details/1999_Game_Developers_Conference_Audio