Very interesting concept, I don't think I've seen it before. I know there are games where you place magnets and whatnot, but not ones where when you place a magnet, it actually has two opposite poles, which are some distance away from each other.
As someone who's working on a project with a "torus-shaped" 2D map, the way the black hole looped around into the other side of the map when placed caught my attention. Sadly, the boxes collide against the edges of the map instead of looping around. I think it would have been really cool if they looped around too and it would have added an opportunity for deeper puzzles.
I wish it showed me a preview of where the placed black hole would be. It was frustrating when I placed a white hole and the black hole turned out to be on the other side of the map, which is the exact opposite of what I wanted to do. I know I can just consult the numbers at the top-right, but the player should be focused on solving the puzzles rather than the grid intersections.
I think the 3rd level has a bug - there seems to be an invisible collision shape right below the source portal.