Dude, I am chilled!!! It's all good. Original would be something like Shark Shark. Making Shark Shark one player vs the computer wouldn't make it original again.
Saying Super Space Patrol and D2K are substantially different from their original versions is like saying World Championship Baseball is substantially different than Baseball (hahahahhaha) Now, World Series Baseball is substantially different than baseball. Maybe we need to define "substantial". Now if you are talking about a few changes or additional levels, then I think Samegame and robots would fall into your category. It appears to be more than just a re-release.
Do you have the inside scoop on Minehunter? It sounded like it was going to be updated / changed, or as you would call, made to be original.