Glad you enjoyed it, yeah the slow movement was to get the player to make early use of the upgrade menu.
Each blue pixel disappears after you've fired it ten times. I couldn't find a good way to get this across to the player in a concise way. I dismissed the idea of having some button combo or menu option get rid of blue pixels too since it seemed too fiddly. It's something I'll have to keep looking at.
Thanks for the feedback! :)