The Fallout RPG series is one of them, and with a complex character development system and many skills to choose from, you can spend literally hours tinkering about with your characters, fine-tuning them until you have a squad that can deal with any situation the game might throw at them. but there are few modem day examples of truly great turn-based games with futuristic leanings.
Fantasy fans and those with a leaning towards Civ copycats are fairly well catered for by PC games right now.
