You don't get much more retro shooter than this!
Everything feels right, right from the get-go with that garbled "Radmars". The art is beautifully grotesque, and has no qualms about telegraphing its inspirations, which is great, I think.
I do wish there was a score system, or Gradius-style pick-ups, or something to give me a reason to shoot enemies that aren't directly in my way. But I might be nitpicking.