So I absolutely love the game; but I'd say the game's biggest weakness is that when you save, it's not always saving your progression.

For example, I had two ship pieces and the meteor when I seemed to be stuck getting the last engine piece from the far left slot (literally moved every piece of "junk" out of there so that it was just lifting ET games; and still the magnet couldn't seem to find the engine piece no matter where I moved it) - so I tried to save from the crane - when I found the "Empty Slot" bug (reported here - https://itch.io/t/1082992/v4-attempting-to-save-a-game-from-the-crane-shows-all-...) - saved and restored (just to see what would happen restoring from the crane save slot).

Boom. Ace is at the front of the junkyard, in mule, and all progress was lost (no longer had the pole, the two ship pieces, meteor). So you need to know where to save where it's safe to know the game has all your progress saved.

This could be a major turn off to someone, whose done a bunch. Saved. Came back. And all that progress is gone.

Let's put it this way, if the game is released with a save system like it has now, it will be mauled. I can just barely tolerate it for a beta version myself. 

I mean the work around would be to do "Check Points" in the game. So the game auto saves your progress at specific points. And just remove the manual save. Plenty of games go this route. And since - as far as I can tell - there's been no way to dead end yourself - the "check point" option wouldn't be bad. Just takes away the convenience of saving and quiting whenever you want.