Great concept, unintuitive interface. I wound up figuring out each puzzle long before I worked out the muscle memory to execute it in time.
The most unintuitive part is how you have to constantly switch fingers to select and then turn items. If you assign Item Select to key 3 and Wall Break to key 1, all Item functions could be done by the index finger.
Stretching my hand to hit R for every restart messed with my muscle memory, too. Right-click would be easier.
Hope this helps, and cheers!
EDIT: Thank you for the response! I now see that WASD for arrow turning is an option, and a much better one. I'd go even further and set WASD to each place a directional arrow with a single click rather than 1 click set and another to turn. I'm assuming that directional springs can also be turned, in which case you can select, say, a right-turning spring by pressing D twice.
Wall destruction could also be done with a single click rather than having to first hit one key to select the pointer and then another to use it. Making the shield key a toggle would also help when switching back and forth between it as you often have to do quickly. Perhaps both could be set to the right-mouse button: click to destroy walls, hold to block bullets.
This way, all keyboard keys are dedicated to item selection, easier to mentally categorize.
Cheers!