Steam games that won't open

Postal 2 :( (works on linux though)

Half of your games is alot, I think the problem is at your end.

I have this problem with Velvet Assassin, not working on Vista and 7(solution to the problem apparently exists but in my case does not work)...it is a problem mostly with old games but it happens sometimes with new

Many games run into problems depending on your OS. For example GFWL can give you issues with Windows 8 (It did for me)

Shufflepuck Cantina. It literally won't open no matter what I do. I had no intentions of playing it anyway, I just wanted to idle for cards.

Risen. Still more interested in the cards than the game, but for the longest time it just FROZE on the logo and then crashed. I did eventually fix it, though. Even got a foil drop from that. I think the game was apologizing.

If you have troubles while trying to play The Witcher 2 on steam, you can always redeem it on GOG, and play it DRM-Free... I'm planning to preorder The Witcher 3 on GOG, because i'm becoming sick of Steam issues like the ones you mention.