Hi,
there was an issue with the valve turning in one of the versions and I'm currently not sure if the newer one has the fix in it. (Just don't turn it, to avoid this issue)
As for the last puzzle piece, the asteroids have movable ice cubes. You need to refill the stove, back of the spaceship in the inside, with one ice or coal cube. Also there is a pickaxe hidden between the astroids to the right, if you are leaving the ship through the hole.
This game was made for a one week gamejam (https://www.gdwtrier.de/startseite), but it will be shown again in one or two months, so it might be improved and fixed at a later point.
For now we all are exhausted, and will be taking a break for a few days/weeks.
Thank you for playing and leaving feedback!
Best, Felix