Thank you for playing! The color palette was not intentional. I just thought it looked wonderful hahaha. I tried to pitch shift the sounds every time it plays so it wouldn't get boring, but maybe because the range is too small, that causes it to be repetitive. I have come up with a few other upgrade ideas, but I have been so busy with school recently that I don't have enough time to actually put them in the game and try to balance the upgrades. As for the lag, I'm not quite sure myself what the problem is, because when the upgrade panel is active, the timescale is 0. It shouldn't spawn any bullets at all. I will try to look into my code. I thought the difficulty was okay and maybe even a bit hard for some players, that's why I make the EXP fly into the player.