They're both fantastic games, but the original (in which you go to Hamburg and a space station) felt more adventurous rather than the more grounded sequel (in which you go to the arctics and even more exotic locale: my hometown of Calcutta). Set it in the fictionalized disco-themed cold-war with the lead jet-setting around the world, and we're golden!
Also, only a single game, but: Arcanum. (At least this one's possible to buy on Gog and Steam...)
Arcanum supposedly had a sequel in the works at some point: Journey to the Center of Arcanum, and frankly, while I'd prefer to see other continents on that world explored a là Around the World in 80 Days, I'd still be sold on a hollow-earth adventure any day!
I keep hearing that, but it seems like if there was a market for a 60s-themed spy game, someone would make a game that's totally starring Kat Bowman who is an agent for ACCORD.
Sadly it's probably more that uh, there isn't and now I'm going to go sad replay NOLF again.