The visuals of this puzzle-game-in-development caught my eye & the concept of being inside a synthesizer sounds pretty cool. There's a downloadable prototype at the game website.

FRACT, an in-development independent game from Montreal-based Phosfiend systems is, essentially, a music/puzzle game that combines elements of Tron andRez...before putting players inside a giant synthesizer. In the development walkthrough above, Richard Flanagan and Henk Boom walk players through a big chunk of the game where, by solving puzzles, they activate different parts of what amounts to a gigantic synthesizer, then connect the parts they've activated through a giant, walk-up pattern sequencer to create original music. 

Article at Kotaku

Game Website