This is a nice puzzle game. There are a couple of things you could improve to increase the longevity of play.

Positive aspects

• Simple, clear goal = Relatable setting: Space station, boxes.
• Puzzle difficulty increases gradually

Area of improvement

• The third level introduces a difficult approach without teaching the player how to first
• Clunky and unpredictable controls - the lack of control degrades the gameplay experience (creating frustration). One way this could be fixed is if you allow the snap position to grid and snap rotation of 45 degrees CW/CCW and then turn on physics when gravity is switched.
• Variety - A new gimmick should’ve been introduced after a few levels to keep engagement
• Any box could go in any slot - I finished the last level just by stacking boxes, it seems like the system doesn’t check which box is which or its rotation.

A solid puzzle game, if you fix these things you will essentially have a game, which you can then fill with levels and ship.

Very cool!