Case in point, I know three people who have upgraded to Windows 10 in the last couple of days (including my brother, who got in line for Windows 10 well after I did... and yet I still haven't gotten my upgrades yet... go figure) all called me complaining that their games no longer ran on Windows 10. I asked them if they had updated their Video Card Drivers, they said they hadn't. I told them to, and suddenly everything worked just fine again.
Microsoft made the decision, probably to save on bandwidth, to only include DirectX 12 in the Windows 10 Installation. Any programs that run DirectX 9 or DirectX 11 simply will not work on Windows 10 without getting your drivers updated. I would think that this would be common sense, to make sure all of your drivers are updated... but apparently not.
And yes, I do know that I can go out and get it, I have several ways of going to get it actually. But I do want to go through the upgrade path just to see what it does so if someone has a real problem with it, I'm not going on what I've heard someone say, I can see for myself what it was supposed to do, and compare it to what it did. If I find a problem with my own install afterwards, I have no problem doing a wipe and Clean Install. So far I have not seen or heard of anyone going from 7 to 10... that might be why my brother slipped in ahead of me, he was going from 8.1 to 10.