From its homepage:

 xpuyopuyo is a UNIX port of a very big time sink :) . Puyo puyo is a puzzle
game, somewhat like Tetris, where you strive to match up four "blobs" of the
same color. Each match you make gives points, and also dumps gray rocks on
the opponent which are irritating and troublesome to get rid of. Multiple
matches at a time score more points, and dump more rocks on the opponent (a
quintuple-match will dump around 20 rocks on the opponent, all at once).

 We ported it overnight to Linux, so we could play whenever we felt like. The
AI's evolved more slowly, over the course of a week or so. I welcome sugges-
tions on how to make the AI's more difficult during the game; currently, they
are rather easy to beat on easy level, but more difficult on hard. There are
still gaping holes in the game interface which should be fixed soon. Sugges-
tions for improvements are welcome.

WWW: https://chaos2.org/xpuyopuyo/