If it came down to my top game it'd probably be a tie between Master of Orion 2 and Heroes of Might & Magic 3 Complete.
Surprisingly, I had never played HoMM 3 until just a few years ago (sometime before GOG came on the scene) - I kind of missed out on a lot of games around the turn of the millennium and the early 2000s - though I had played the first two before it in the mid '90s, which I quite enjoyed but (puzzlingly in this case) didn't think were the bee's knees. There were always one or two people saying extremely good things about part 3 that I finally gave in and hunted down a copy out of sheer curiosity, and boy did I get hooked good!
As for MoO 2, I snapped up a copy as soon as it was released - a definite rarity back then for me - after repeated reading of its original reviews. I had a real big soft spot for MoO 1, and now that the game was becoming bigger and better it was pretty much decided for me before any part of me could even consider saying "no". Turns out my love for the game was so big I just had to show it to my friends, so I brought the game to their places so they could check it out, and in turn they ended up buying it too. That didn't happen often (as good as never again). We also had some quite fun hotseat sessions with it back then.
Anyway, it certainly helps that both of these games have pretty much infinite replay value. Yes, I've had incredible fun with other strategy, adventure, role-playing, shooter, space sim games and so on, but the above mentioned never truly get old. They sure are getting on in age, but they're just as great now as they were then. It truly shows that great gameplay and core design trumps all. That doesn't mean I play them incessantly. There are longer stretches of time when I may not touch them at all, but it's always a good time coming back to them when I feel the urge.
Post edited April 20, 2012 by mistermumbles