There are a handful of tech demos that will run, including a shooter, the Dolphin demo, the Apebot demo, and a couple of others. In terms of a playable game, there is IMSA Racing which was extremely close to being complete and is a good bit of fun.
Backwards compatibility with 3DO was something that was being touted when M2 was first being discussed, but unfortunately they killed off that idea fairly early on in development.