It’s a decent game, though there’s lots little bits of polish missing. Probably biggest complaint I have is using filtering for sprite upscaling rather than nearest neighbor. Some sprites do that, some do not.
It is definitely nice to see 3 levels. I think this game is missing some sort of dodge mechanic, maybe a way to swat bullets down? Level 3 gets pretty challenging and feels like you almost need to get lucky to get past the beginning.
Still, I like the idea of saving the world across time, with increasing levels of anacronism.