Feedback (Keyboard and mouse)
1. Menu
I think a separate back button for the controls and the pause menu is definitely needed. Having to press esc in the options menu unpauses the game automatically, which can get annoying.
In addition to that, in my opinion, a "back to main menu" button is missing from the pause button.
2. Controls
Not much to say here, felt great overall after remapping the jump to the W key.
However, when throwing using the mouse, I found it counterintuitive to drag forwards to throw. I think from playing games like Worms and Angry Birds it is engrained in my hands to pull back to throw forwards. While I don't think everyone agrees with me in this regard, an option to toggle between those two would be nice.
3. Gameplay
Once again, good overall, though I do have a few points to consider.
For one, in some levels (or level, I only noticed at the last level) it is annoying that the magnet spawns behind the character. As it took me a while to figure it out, having to run back after each reset made it quite annoying, with me often leaving the magnet behind and having to backtrack again.
Another thing I've noticed is that there is a slight cooldown when changing the polarity, meaning you can't rapidly change it. While it probably makes more sense balancing wise, it would be nice to be able to change the polarities more quickly, without having to wait for the animation to finish.
My last point is to maybe have a dedicated place to give feedback so that it isn't spread out between different platforms. Maybe even putting a link to where you can give feedback in the main menu so that it's easier to give feedback directly after playing.
I really like how the game is coming along. Keep up the good stuff!