.....get the Hell mod after you buy it. Improves the game by about 1000%. Mordor still working on the Hell 2 as well. Guessing will be done in the next year. More classes, tons of more uniques, more quests, and a shared stash. Not to mention more character classes. The Hell2 is going to have a boatload of more classes. And, multiplayer is also awesome in all versions of Diablo 1.
EOB 1 and 2 were among my earliest PC game loves.....wore headphones and it was downright immersive for me, delving into those dungeons. Even got creeped out a bit hearing the telltale sounds of the impending monsters. Highly recommended. It's been so many years, I just might play them both again!
Didn't even realize GoG had added Civ 4 until I just saw the bundle in the Holiday Sale......wow.....I used to think Civ II was the game of all time, until Civ IV came along. I still play it to this day! And, after over a decade, that's saying something. If you have not played Civ IV, do not hesitate any longer! The one thing I'd recommend is getting the Buffy mod at CivFantics.com. It is a huge improvement to the interface, and you will not want to play the vanilla game again, once you play with this mod. Now if GoG adds the Diablo games, they would have the two most replayable game series' ever. Civilization and Diablo games have caused me to have a humongous backlog of other computer and video games! I still cannot stop playing them, to this day, 15 to 20 years after they were created!