Some more I was thinking about that I totally neglected to mention:
Sid Meier's Colonization
Man, I played this game solidly for a couple years straight and would come back to it constantly until it no longer ran on my newer systems. Now, that being said, there IS a version out fanmade, I believe but it's pretty buggy. Getting the classic version with the GoG treatment would be freaking awesome and an instant buy for me.
Sid Meier's Civ 1 and 2 with Civnet ofc. :D
Do I really even need to add a reason why? ;)
I Have No Mouth and I Must Scream
One of the most disturbing games I think I've ever played and a must have for any adventure gamer out there. (As long as you're not squeamish.)
If you're not into ultra deep 4x strategy TBS games, then this probably isn't for you, as it's not very graphically pleasing. Yet somehow, even as dry as the presentation was, it had that "just one more turn" factor that kept me clicking long into some late nights.
Avalon Hill's Advanced Civilization
If you're not into the type of games that AH's foray into computer gaming offers, then this MAY NOT be for you, but I enjoyed it immensely, even if it did feel a little like a straight board game port. (Hey, it worked for Risk.)
Inca 1 + 2
Was a pretty under rated adventure from an era when Sierra pretty much owned the genre.
Warhammer Shadow of the Horned Rat and Dark Omen
Both excellent fantasy strategy games. Build your armies up, earn money from winning battles while taking the least amount of casualties possible, use battle magic to increase your odds of winning. Setup spear pickets for your ranged units and send cavalry into the enemies' flanks!
I'm sure I'll be back again when I think of a few more. :D