If you're worried about certain company, may I suggest using games that were on the NES but weren't not trademarked by that company. Like Gradius/Nemesis, Castlevania, or Mega Man.
I'm impressed about your insights with 7800 graphics. I designed the character graphics for b*nq. While people did like the designs, I always felt more could've been done with it. Now I see evidence that more could have been done.