I picked up some PlayStation 1 games that I want to sell but they have a lot of scratches so I don't know if they work. I started out of disc one of each game and the beginning movies played fine and I played through some of the game with no problem, but have no idea if the other discs 2-3 will work as I don't have any save files.

In short, how can I verify that these games will play all the way through?