Xtris was written by Roger Espel Llima, and the release that I have was completed in 1996. It is a Tetris clone for X windows on unix like systems. It works on most Unix systems and I played it on NetBSD. The game plays pretty much as you would expect a Tetris game to play with one major difference.
Xtris is essentially multiplayer, the program automatically starts a server and connects players on the same machine together for competitive play. The rules are pretty much the same as ordinary Tetris, except when a player makes enough lines another player has some blocks added to their play area at the bottom pushing what they have up. This can fill up a players play area quite quickly if they are unlucky, and obviously cause their game to be over. The game continues until there is only one player left and after a few seconds a new game begins.
If you find that you are alone on the machine you are able to start-up some AI players (called bots) to play against. The AI isn’t as good as human players and I can pretty easily beat it by basically playing faster than it does. This is obviously a lot more difficult to do on faster speed settings, so if you want a challenge increase the speed. Also if you are not interested in playing against other players you can choose not to. Although this does require a command line switch.
The graphics are pretty simple, and travel over the network (via X) without any trouble at all. I used my Sparc station to play the game, and had no performance issues at all. I didn’t have any other people to play against so I can’t comment on what it’s like playing against other people. Playing against the bots is challenging, but not overwhelmingly difficult.