I really like the concept and the atmosphere. The breathing sounds are add a lot to the overall feel of the game. It is rather difficult though (hard to find the food and oxygen goes out quickly) but maybe that's part of the concept.
One thing I am having trouble with are the control. I always find myself trying to use left/right to turn from the position the character is facing (not as absolute direction). Maybe that's just me though.
Great game in any case