Extremely clever use of the concept and I love the simple but effective art style. I really love how the clock enemies' health bars are their clock arms (and I wish that also applied to the hourglass enemies)
Really the only thing that's missing is upgrade variety, stuff like triple or exploding shot, which is hard to put into a 4 day long game jam anyway, so kudos!
Edit: apparently triple shot DOES exist it was just rare enough I didn't see it my first time. Neat!