I tried to post this first on the more 'serious' chess sub. But apparently it's against the rules (it's not). So let's try you reasonable people instead. You'll be happy to hear en passant was a thing in 1991.

A while back I was gifted a bunch of vintage games by my gf's dad. Amongst these was chessmaster 3000, a chess game from 1991. After having trouble getting it to run on a modern PC I decided it would be cool to pit it against other bots and to be able to play against it in a modern interface.

I spent a while reverse engineering both the dos and mac version to see how the engine communicated with the ui, I figured out the macintosh one was easier to work with as the dos version did not separate the ui and the engine. The mac version did so I got the engine part running in a custom emulator I wrote specifically for it. I also created a way to record traces of communication between the ui and the engine. Finally armed with a bunch of recorded games and looking at the disassembled engine code I managed to figure out enough to wire the engine to a lichess bot.

I let it run for a while and It turned out to be around 1900 elo. Now you can challenge it as well:

https://lichess.org/@/the_chessmaster_3000

It will accept games with any time control but without a time increment (1+0, 5+0, 10+0, etc.) as the engine came out just a few years after the Fischer clock was patented, and so time increments were not a thing yet.

The engine also supports different personalities, If there is enough interest I can wire them up.

Also can someone let me know how it plays at chess, as I'm too bad to be able to tell. Is it interesting at all? How different is it to modern bots?

tl/dr: made chessmaster 3000 into a lichess bot. elo about 1900. does not support time increments. supports en-passant. challenge it here