I absolutely love the art direction for this game, especially the cover art! The variety of bullets that you can use are intriguing as a concept and being able to pick which enemies you want to fight is also an interesting idea! However, I do feel it's a bit difficult to keep track of which bullets do what during gameplay, and I found myself repeatedly checking the store page while in the select screen.
Also, I think it would be very intuitive if the R key was used to both start and stop the barrel's spinning instead of having to press RMB after pressing R. Some more music and sound effects would also be welcome as well.
Otherwise, fantastic work on the Jam!