The Ghost of RubangB on 30 April 2010
Once you learn how to out-cheat the computer in Puzzle Quest, it's too cheap and easy and not even fun anymore.
My favorites are Tetris, Dr. Mario, Minesweeper, Picross, Puzzle Bobble (aka Bust-a-Move), and if we're including it, definitely Portal.
EDIT: Forgot World of Goo and Hexic.
