It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

Will we be able to play with owners of the games on Steam?
I posted same question on Steam Community page. The answer was NO. Have GOG version. Feel quite sad about it. Btw can add me, want to see what it's like.