Mostly modified/custom .dll (nameless things) and some games, though many will work if I jump through some hoops.
Starcraft 2 was broken for months and I still see occasional reports of it crashing. It crashed for me back when I had given W10 a try. It appears to be driver dependent, but many visual novels don't function or will crash or need to be ran in a compatibility mode (and may be missing audio when if that is done).
A few things I rely on have been updated to support, others will never be updated (due to dead development). For example, QTTabBar (a shell extension for Explorer) has been updated for nearly a year.
I use W10 at work and have no issues with it. I will probably be purchasing a W10 laptop soon for when I travel. But I have to jump through far too many hoops to update my home machine.
My real issue is I should be using a UNIX machine that gives me total control over everything without ugly hacks and disabling half the OS (almost literally...) to do what I want it to do. :) However, back when I built my machine, the games I was playing wouldn't run on Linux so I was stuck with W7. Now my station is so customized that replicating it on Linux isn't worth the effort in my eyes....