You can't fold across occupied tiles. The tile the player is in is also considered occupied. However, the player can be in the middle of two tiles and both will be considered occupied. I agree that it can be a bit finicky. I'll be reworking that in future versions to make it more intuitive.
I currently have a lot of ideas for the space compression mechanic and am working on a post-jam(and perhaps even a full game). The full version will be a separate game on itch. So in order to be notified when that's released, I recommend following me on itch.
Thanks for the image. Yes that left marked tile can't be folded since the selector would have to start at one of the columns the player occupies. There is a in-game rule that "you can start folding from an occupied tile". Though laser turrets/flags etc. allow it, the player occupied tiles don't. I had to skip that due to time constraints during the jam. I will fix that.
