If you're a fan of Dominoes and Tetris-like games, you should enjoy Domitrix.
The more domino-type blocks you link, the better your score. Watch for the solid green block; you can use it to delete several others and pick up bonuses.
Domitrix features colorful graphics and over 40 minutes of original music. You can customize the arena by adding blocks and play with or without gravity for a different kind of experience. However, in the unregistered version, the play only lasts for 8 minutes at a time.
For more detailed information, including on updates, please read the documentation or visit the home page.
Requirements are: any Power Macintosh, System 7.5 or later and QuickTime 2.5 or later.