A fantastic game! The concept is quite good and in execution it is very well polished. The art is really nice with animations having a certain crunch to them that really makes every hit feel great. Music had me really focused in on what I was doing, so that's good.
I second what others might have said regarding the speed of the clock hands in later waves. In such scenarios, I found that it was better for me to attack the enemies one by one with the big clock hand than to spend time positioning the smaller clock hand.
I'm sure something could be added to influence the speed of the clock hands, if only temporarily. I also really wanted to move AND shoot at the same time but could not lol
Overall, great game!! :)