Hi.
I just wanted to mention that I just completed my upgrade to Windows 10 and it's really nice. Everything seems to be running nicely but there were minor hiccups that I fully expected. Most importantly, both Sims games survived it with minimal trouble.
Both games, upon detecting that I had a new graphics driver, started up in their safe (lower resolution) mode - making me re-set all of my game options. But once I did that, both games ran just fine. The Origin client couldn't connect to the service on the first try when I first started The Sims 4, but it worked fine after closing it and trying again. Works fine since.
Some people are fearing this Windows upgrade so I just want you to know that it all worked great for me and I am very pleased with the new Windows. I never quite got used to Windows 8 but this one seems to have gotten it right.
My only advice before doing the upgrade is to make a note of ALL of your game options preferences (from all of the Options tabs) before getting started because it will forget all of them. Also, if you can, make a full backup of your system drive (c:) before getting started in case you need to back it out.
