LOL, I've just discovered your youtube videos after searching for "river raid godot" (after spending some time playing original RR on archive.com I wondered "if anyone code its clone in Godot"), then found this page to found out you've cancelled game a few days ago? :)
What a luck... Damn... The game looks great. Congrats. I don't think Activision or Atari would mind you did this clone, but I'm not an expert. :( You do you.
I wish I found this page a week earlier... :)