I enjoyed playing, love the sound track and dig the art theme. A menu/quit game option would be nice so I don't have to alt+tab to exit the game. I thought the intuitive UI design was really well done (e.g. you use obvious controls (awsd) or train the player when events happen, rather than a bunch or training tutorials), I also like how there are some area that double back on themselves and then change open paths. I really liked the oxygen refill concept, reminds me of some old commodore 64 games I used to play as a kid (as does the art theme somewhat). Dying and having to go all the way back to the start was a bit frustrating for me, maybe if you just went back a shorter distance e.g. when you pickup the drill, just go back to 5 or 10 seconds before. Finally, the into story was cool, you did a good job of starting things off in an interesting way, well done!