Pretty good concept and first GWJ so nice job. I'll parrot some of the other comments. I didn't have much trouble with the enemies. I got into a rhythm and stopped needing to freeze. I was killing things before they were even on screen a lot of the time. There was a bug with the freeze mechanic you can retrigger it while its active giving you more time in the frozen state. Not sure if that was intentional but it did allow for an easier time marking all the enemies. I got to over 2,000,000 points and over 500x multiplier and called it quits. Really all this needs is an ending or a difficulty ramp that eventually becomes overwhelming and you've got the full package. You could also consider a cool down on shooting or some kind of ammo/reload mechanic so it mattered more that my shots hit or not.
In the end I had fun and was just missing the closure of an ending