Yes, it has happened to me, but not with games, but with cheapass optical media.

In fact, ever since I purchased two BDRE drives on my computer, I've started to backup files extensively, specially when I encountered some of the first few CD's burnt to be pretty much screwed up with bitrot. These CD's are from the year 2000 or so, so yeah, they are old. Generic media doesn't help either, though to be honest, generic media isn't always generic as people think...

Anyway,I've noticed that the conditions in which the discs are located in play a very important role in bit rot development. In a sealed environment, with little or no humidity, bit rot was practically non-existent. But when exposed to the elements...bit rot was just ONE of the problems to plague optical media. Others include fungus, stains, obviously scratches, peeling from the label side...and much, much more.

I'm pondering about putting small silica packets in certain games/locations to help prevent this as much as possible. Or at least slow down it's progress.