I used to love Text Twist, I've burned out on it, and I can always beat the computer at Hexagon.
Same with Risk.
Word Racer gets old after a while, too.
Poker's no fun unless you're playing with real money. (Someone always
raises the max each time and turns out to have a crap hand, unless they have something real to lose.)
Tower defense games can be amusing for a while.
I gotta find a new game.