auditorium
Auditorium is a very elegant puzzle game by cipher prime. In a kind of playful synesthysia, the goal is to create music by directing colored light beams. With a visually stunning interface and orchestrated music that doesn't get annoying (a real feat in an online game), Auditorium makes the process of tweaking the puzzles a rewarding experience.
Though the game already has over fifteen levels, it's still only a demo, with a full version promised in the near future. They're accepting beta testers for it too.