Fun! And gets quite intense/nerve wracking in the night cycle.
As you call out the biggest missing thing would be a scrolling background. I think this would have made heaps of difference to the presentation. The next visual thing would be more varied obstacles, but that’s probably just finding more sprites vs getting the scrolling background working, which as you write is more of a technical challenge!
I think there’s a bunch of potential here to expand on the basic idea and run with the simplicity and slickness of it. Well done!