I enjoyed playing Loops of Zen:

Loops of Zen is a stark, abstract puzzle game in which you manipulate loops, curves, and lines to form an unbroken whole. Beginning from a diagram like the one in the screenshot, of broken segments and line nubs that lead no where, you click on individual items and rotate them until you achieve a solution.

The simple forms and black-and-white graphics are severe in their simplicity, but the puzzles themselves are engaging. The simplicity of the system lends itself to what ultimately, as the puzzles become more complicated, becomes a set of difficult challenges.

- costik @ Play Thing Thing!: Link.