[greyman]

I kind of agree, chess without promotions, castling and en passant is not chess. But the guy also made full version, with impressively small size:

For real purists: a close-to-minimal version that does understand full FIDE rules including under-promotion can be found here. It measures 1433 characters.

(although I don't know why people who adhere to chess rules are called "purists", but whatever. :-))

[xwdv]

In Ultima Online we would play chess to pass time on long sea voyages while hunting for monsters or treasure.

There was no rules engine, it was just a simple board where you could drag and drop pieces around on any which way, which allowed for a lot of flexibility in how you played. We could even play random chess this way.