Ok, I'll try the "beta" option in Properties, but I am not hopeful.
Oh yes, of course it meets the requirements! It's a now-aging mid-2011 iMac, but it certainly can handle such games. As I have said, the demo works just fine, which is proof of that, I should think.
I would presume Chris would answer you before me, but I'll try in a day or two if I don't hear any updates from you.
At this point, I'd really just like keys for the direct-download versions of these games. It seems the way they interact (or don't) with Steam is what is causing the problem, as far as I can tell, and it seems like working it out somehow will be long and exhausting.