Spending large amounts of time playing it ten years ago, and spending large amounts of time playing it now. A classic.
It stays fresh via the subtle - yet important - changes each civilization has to offer, and the different game modes which allow you to play as your mood depends. Most of the building changes are aesthetic, but they still offer a nice change. Most of the difference comes from the units that you have available.
The storyline offers many rewarding experiences, despite being short and hard to figure out or find your objectives. Despite most of the game being in Skirmish or multi-player modes, this is a nice addition to the game nonetheless and allows new players to be eased into the game so as they are ready to play against others or in Skirmish.
A brilliant series ten years ago, a brilliant series now.