Age of Wonders: Shadow Magic is the third installment in the Age of Wonders series. It was developed by Triumph Studios and published by Gathering in the Summer of 2003. If you have never heard of the series I suggest you read the writeups on the previous games before you go much further.
The game itself is a turn based strategy game, similar to Heroes of Might and Magic, that takes place on an isometric hex map. Shadow Magic uses the same engine as Age of Wonders II: The Wizard's Throne, but the designers at Triumph have redesigned many of the sprites and added new features, such as a random map generator. There are three new races (Syrons, Nomads and Shadow Demons) and each old race is given new units and buildings. Even though it uses an old engine, the game is not an expansion pack. It is free standing and an excellent place to jump into the series.
The game plot begins with portals to another dimension opening up all over the landscape. Huge, insectile Shadow Demons come out of the portals and generally raise a ruckus from hither to yon. A group known as the Phobians try to use this to their advantage by turning the populace against anything magical. The chief wizard Merlin enters one of the portals to determine what is going on, but the wildly different laws of magic in the shadow realm weaken him to the point where he is unable to resist the Shadow Demons.
The game starts with you playing as Julia an elf queen and a fellow wizard to Merlin. You have to help unite the circle of wizards, hold off the Phobians, and eliminate the Shadow Demon threat.
The sound effects are excellent. The visuals are stunning. It is has a steep learning curve, but the tutorial missions should give you enough to understand the concepts. I'd give it an eight.