Kohan: Ahriman's Gift. It's about 8 years old now, but still has an online community. Probably one of the most intelligent gaming communities out there. It's a real-time strategy, based in a fantasy world, reminiscent of Lord of the Rings, or Wheel of Time novels. Very innovative, great 2d graphics, and steep learning curve. Using real-world combat strategies such as flanking, ambushes, etc. Very interesting balance between economy and military, and is not micro-intensive. In the online community, there are standards that everyone abides by, to create a balanced game. Highly team-oriented playing.
I would compare it to chess.
I highly recommend it to anyone looking for real-time strategy games, but the likelihood of actually finding the game and a cd key are low.