Loved the demo, but this review will be pretty critical despite that
The throwing felt a little weird because you can jump but not move left and right, which isn't terrible on it's own, but with slants on the floor and ceiling you can slide down the slants during it, and jump into stuff on the ceiling to move as well.
This could very well just not be what you intend for the game but I'd love some momentum mechanics with the magnet, and maybe another speed to build up to kind of like max speed in Super Mario 3D World
The jump I think could use a little bit more springiness, when you hold it you kind of just end up floating up slowly for a bit, which feels slightly off
You probably already have this on your to-do list, but I think the menus should probably be themed in the pixel art style the rest of the game in. Although, the settings tabs need no changes, they're already beautiful
I think a visual cooldown for the magnet would be helpful if instantly switching it back in forth isn't something you want to ad
Adding multiple magnets could be a very fun mechanic, but would require testing