I'm not on 8.1 at the moment, but these are the ones I remember:
Not even starting: Sim City, Path of Exile, Deadly Premonition (if this counts, but it at least starts on my 8.0), Eschalon: Book I, The Testament of Sherlock Holmes, XCOM: Enemy Unknown, Kerbal Space Program, Driver: San Fransisco, Robin Hood
Games with issues: Stanley Parable, CSGO, games that doesn't use raw input
I could try reinstalling 80 games, but I'm not reinstalling 80 games for 8.1. There's simply not a single particularly useful feature within 8.1 so I'm perfectly fine with 8.0.
In my opinion, not worth the risk. But if there's a feature you really want, try it out, and be sure to make a clean install and be prepared to apply the recently added fix to all the games without raw-input, if you want to play with a mouse.
Yeah, but that's not a fix, it's a workaround. And you need to apply it manually for every game without raw mouse input (except for those 10 games they included).