arcTron for Mac

From Qhex Design:

This is the familiar game of tron, but played along polar axes rather than rectangular. As in tron, you are a motorcycle that creates a wall behind it, and you must avoid crashing while attempting to trap the other player. Rather than moving either horizontally or vertically, though, you travel in either a circular or radial path, analogous to the polar coordinate system.

This is two-player only, and not complete; it's almost a basic proof of concept.