Audiomata
Click on a square to activate it, click again to change its orientation. Press play to set active squares in motion. Tones are sounded when an active square hits a left or right wall. Which tones are sounded changes when an active square hits a top or bottom wall. When squares collide, their orientations change by a single clockwise turn.
The basic mechanics are based on Batuhan Bozkurt's Otomata, but because of the twist in which the top and bottom walls change pitch mappings instead of sounding a pitch, the output tends to be somewhat less note-dense and has the potential to be both somewhat more dissonant and varied.
Feedback is welcome, either via twitter, or email (obtain the address by replacing the dot between my domain and subdomain with an @).