GOG - Crusader No Remorse, IL2 Sturmovik

Steam - Fallout 3, Deus EX, Syberia, Stronghold 2, Space Trader, Snapshot, Scoregasm, Shank, The Ship, Little Inferno, Left 4 Dead 2, Far Cry, Cities in Motion and many others.

Conclusion: GOG games are more expensive to me (because of local currency conversion mostly), so I take more time to wishlist the game, looking for reviews, see GOGers opinions about it, try a demo and etc. Mostly Steam games were bought on sale with limited time promo and the discovering process wasn´t made properly, resulting in a lot of deceptions.

Being a huge Arcanum fan, when I heard Troika was making Temple of Elemental Evil, I was so excited.
When it came out it was rather disappointing, played it for couple of hours at most and perma-uninstall after that.

Alien Colonial Marines (with season pass).
I completed the main campaign, then I gave up on the DLC...this game is a giant poopy.