Airlock

You're stuck on a broken moon base and the airlock is sealed. Grab all 10 oxygen cells to open it and get out.

Your suit is leaking, so your air keeps going down. Cells fill it back up, but some of the first ones are duds that zap you and take air instead. Near the end there are levers that flip gravity, so you run on the ceiling.

Controls: arrow keys or A / D to move, Space / W / Up to jump (press again in the air to double jump).