The only game systems I've had time for have had rich depth but fairly simple rules (QAGS, James Ernest games, etc.). As a gamer on the go, what do you play for quick but complex and enjoyable games?

I find the simple quick games on Facebook on the PC to be very addictive and fun at the same time. You can play for short periods and not get stuck all day on a game. But if you have time, you can play as long as you want. Farkle on Facebook and Bejeweled are both very addictive.

I happen to have a Palm Treo 680 on which I have a game called PalmIshido. The object of the game is to place tiles, and the tiles must match two ways: in color and in image on the tile, so placing tiles takes a strategic mind. You want to place as many tiles as you can. If you have a Palm, it's a game worth trying out. Also, I tried out a game called Senet, an ancient Egyptian game, believed to be the basis upon which backgammon was developed. Senet was really fun. Also, I have a Palm game called GoMoku. The object is to place five stones in a row while you keep your opponent from doing the same. Simple rules, not-so-easy to accomplish. The actual game is called Go. I believe it's a Japanese version of chess. It is played to exercise one's ability to plan strategically. I love it.