This is Remembering. It's a "poetic exploration game driven by sound". It's finished and available for download here. You should go ahead and do just that.

It's a wonderful little experience. By stripping away all but the most basic visual elements, the game - and your interpretation of its world - is powered mostly by sound and music, as you explore stages experimenting with music and keeping an ear out for the changes that slowly bleed into the soundscape.

Remembering recommends you play it with headphones. You really need to play it with headphones.

Remembering [Game Site]