Hello!
First off, thank you for the amazing feedback. I can definitely relate to this being like a TD game because of the different cubes and their behaviour.
Those features and changes you suggested would have definitely had a good spot in the game. I had actually thought of adding a timer before but it ultimately came down to the time that was running out for me so I had to do a little bit of compromises. That visual shooting thingy would've also made quite a bit more sense than it just immediately firing at the cubes. It would have probably increased the skill and (insane) accuracy needed as well, so yeah I'll be sure to take a note of that.
Again, I'd like to thank you for the great and constructive feedback you gave me, especially for that shooting thing I hadn't thought of.