This normally takes a long time and is purely strategy-based.  There are at least 50 different creatures you can fight with, each with special abilities and statistics.  You send "heroes" to bring these creatures around the map to gain resources, experience, artifacts, and other treasures.  Then you use your cities to make more creatures.  Generally, the idea is to wipe out your opponents in stunning, turn-based battle sequences.  The heroes are generally few and they often just explore and wipe out uncontrolled creatures, which may flee, attack you, join you, or offer themselves for hire.  The games take a long time depending on the map, at least 3 hours.  You can make scenarios, and the editor is pretty friendly.  I recommend this game for people who want a slow-paced, strategic challenge.