Connect Four, named KWin4 - played this with two systems ( players ) - easy to setup, just give the IP addy for the server system.

Crack-Attack, same name - you need to look at the man pages for setting up the network connection - again, its a solo game, but, allows for a two player (networked) game as well.

Atlantik - its like a monopoly game, but, for the life of me, I havent been able to get it to work, it is only a network game, you have to set up the board, run a "server" program, and everyone "connects" to it, to play.

Battleship, named KBattleship - played either against the computer, or two player (networked) - see KWin4 above, sets up the same way.

Just a few,
Ms. Cuddles