Its about 1/4th of all games I have.
What amazes me is how good they all work. From all I got, 1 had a dead battery contact, one had a direction-pad logic board wire breach caused by battery acid, and 1 has a slight faded LCD. That's all what's wrong after 30 years, and apart from the one with LCD fade all games are fully working again thanks to easy fixes. And thank god all these games have SCREWS. Not those glued and clicked together un-repairable modern crap.