Curious! Apart from being able to mostly afk through most of it it's an interesting take on this season's jam.
My suggestion is perhaps more pressure to kill enemies?
Viewing post in Clone Invaders jam comments
One thing I intended to do but never got to it was make the enemies decrease your score when they pass the screen. Then each time they clone the amount they take off your score decreases.
So you're encouraged to shoot them but make sure not to go overboard unless they completely fill the screen and you got no where to go.
Maybe this with more speed might add to the fun factor