Lines is another FREE one-player board game for Mac OS X 10.5 (or buy it for 99¢ in the iPhone App Store)
Lines is a classic puzzle game that combines simplicity and complexity, strategy and luck.
The goal is to arrange tokens of the same color in straight lines (vertical, horizontal or across) - rows of arranged tokens will disappear from the board. Get a high score by surviving as long as you can.
* Three difficulty levels - 4, 5 or 6 tokens in a line
* Undo support
* Custom styles for board and tokens
* High scores
* Full screen mode
* And yes, it is free
http://invisiblellama.com/lines/mac