I recently went on a glut of Fantasy Strategy games, buying
Age of Wonders, the complete set of
Heroes of Might and Magic (all the game except 4) and Disciples. Out of them Disciples is probally my favorite for some odd reason.
Part of it is that it is the simplest game out of the bunch, fighting merely involves clicking on an enemy unit to attack, and healing if you have the right troops. The hardest part is "stacking" your troops so that they are effective.
But I am getting ahead of myself. Disciples is a turn-based, fantasy strategy game like "Heroes of Might and Magic", in it you fight on different sides and kill your enemy. As cordelia pointed out there are four different sides, each providing different strengths and weaknessess. I have yet to play them all in any detail, mainly the Mountain Clans and the Empire. But the concept is the same for all; defend your main base, build buildings, research spells, build parties to kill your enemy. Army builing is simple, go to a town, recruit a party leader, and fill out the ranks with different troops. Unlike "Heroes" your party leaders fight in the battles, and can die, however you can reserect and heal any units, including the party leaders. Battles many consist of clicking and attacking your enemy, no real strategy except who to attack, as there is no moving.
There are two ways of playing the game in single-player; Quest, and Saga. Quest is like the single-missions in "Heroes of MM 2" you select a mission and select your side, then play it out. Saga has you play through a campain on one of the sides. The enemy can be annoying, but it can also be very very difficult, I'm still stuck on the second mission of the Empire saga. The story is interesting however, and the setting is very different, with a religious feel. It's really light against dark, with the Mountin Clan the Undead as extras with their own plans.
Over-all I highly suggest this game to fantasy-strategy game fans, and new-comers, as it is addictive, and very good.