Mentioned before, but holy crap, this game has screwed me over for textures, they are just insanely detailed and clear, to the point you can see the individual threads in stitching! It's going to be hard to back to other games I have in my backlog with those huge blurry textures smeared over characters.
Check for an e-mail, there should be a link, or google for the web page that gives it to you, GOG has some page on their site that when you're logged in it brings up the link to click along with providing you your TW2 serial #.
Divine Divinity is the most accessible choice, sort of a Diablo/Fallout hybrid, Gothic 2 is a great open world difficult RPG with a bit of clunky controls and poor UI, and Arkania 2/3 are both great, but extremely, extremely old school, so that will be a deterrent to a lot of people.