One of my favourite real-time strategy games (and the sequel too). You can play as the "good guys" (who try to protect the One Ring from Sauron) or the forces of Mordor. It was a fun, high-energy game regardless of which side you pick. You can command your heroes through the Mines of Moria, sneak through Shelob's Lair, defend Helm's Deep and Minas Tirith, and many other familiar and not so familiar sights of Middle-Earth.
Your heroes, units and buildings can be 'leveled up' (a touch from RPG games) to give them more health and extra powers. Both units and buildings can also receive bonuses (e.g. archers can get flaming arrows). And if you play on the side of Mordor, you can play as Gollum and use the One Ring! How cool is that?
To sum up, this is an awesome RTS, full of action and planning, and very immersive too. I highly recommend it -- it's high time it received another airing!