Nitnendo has (had) a patent on ghost cars (showing a ghost of your former performance in Mario Kart)
Sega has (had) a patent on zooming between camera positions from Virtua Racing 1
Wizards of the Coast has a patent on card games similar to Magic the Gathering. I don't know what their actual patent is but I do know lots of companies paid them $$$$$$$$ for it to have a their own similar card game
these shouldn't be allowed imo