Really cool idea.. I would have loved if the obstacles were like more clear. Some times it feels like i am clearly out of the way but still hit it anyway... My longest breath cycle was 2 :D and I felt the speed boost was a good feature. But i could suggest like the longer you dont breathe the darker you screen becomes forcing the player to do the cycles of breathing to keep playing the game.
Music is good.. Loved the tense yet somehow pleasnt rythm going on.
Kudos for making a fun game!!