I don't use any gaming platforms. Let me know if you'd like help finding that information!
It seems Humblebundle Gamersgate and similar platforms aren't actual gaming services—they function more like stores.
I can't really respond to that. I rely on them all fairly similarly. That's why I preferred multichoise.
I mainly rely on Steam, but I also play a few games on Origin.
Primarily Steam-based content.
Windows games available.