The best part of the entire series

First of all, the best part: You need a patch to run on XP / Vista / 7. The graphics are only 2D and almost stone age standard, but well worth it definitely immerse yourself in the time when the whole world was not so developers graphic horny as today. The Artificial Intelligence is though, once you've grasped it, straw stupid, but the campaigns of the extensions are still quite demanding.
Total: Clear recommendation. Getting started is not easy, but after long-term fun is guaranteed. Be it alone or with up to 20 players.