Thanks a lot for the incredible feedback! @oliver-richmeier ,
-The B key was just a random key I assigned while testing, Since I got very used to it while making the game, I never thought about anything else, and Now that I think about it the right mouse would have made a lot more sense (._.).
-I tried to fix the bug about the upgrades when I had about 3 hours, I tested it between the 2nd and the 3rd upgrade scenes, Perhaps since I didn't test the 1st and the 2nd scenes something went wrong. ://
-The upgrades carrying over was just something I didn't think of, with the way the upgrade system works, It makes sense the upgrades would carry over. My Bad!!
-About the music, I made all of the music in the game, however I didn't have enough time to make original music for each wave, So I just reused fitting music I had already made.
Thanks again for taking the time to play and review the Game!