Lots of tap tap revenge games. Namely the Coldplay release on an iPod touch still running 2.2.1. I also have lots of old ones on my currently active 3GS that was on iOS 4.0, but I finally moved to iOS 6 to get slightly more up to date versions.
I have hundreds of old apps no longer on the store that are still in my iTunes library and can by sync'd to older devices running old firmware. Stills works just fine. Many work on iOS 2.x and 3.x. Most don't work on iOS 7 or 8+, much less iOS 10. Particularly any of the pre-retina apps.
By don't work I mean don't open at all, crash, or don't even respond to touch.
Dug up a screenshot from 2010 back when music games were still a big thing. Man I miss a lot of those, servers have since been shut down and previously purchased songs are long gone. That's the digital age for you.