Thanks a lot for your comment ! You're completly true ! We all felt there were somethings missing while we were playing our game, but we were limited by the time ahah :P
We think that we could add more mechanics as you just said. Rooms with own oxygens, more ships or maybe dash to improve rythm of the game for example. We also plained to add score or timer.
Be sure we will try to update the game in order to make it more enjoyable !