The game is fine with the mechanic, but i found that the multiply of oxygen price is not balance, it should be not double, or it will be hard to get enough money to buy some more x3, also if only you guys got time to exchange those ethan for the main player, but overall the game is already unique enough i liked it so far :D. And the idea the separate the tutorial level is awesome, since its really gave player all the info for the game ;)
Oh one more thing, maybe other already mention this, but it will be neat if i can use mouse to change direction and mouse click to interact :D, and i love how smooth the control is, great job on that ;)