Back in the late 80's early 90's, there were a series of games for the PC called Warlords. This game is a close cousin, updated quite a bit. If you remember and like Warlords, you'll love this game.

As everyone says, it's addictive. It combines the concept of "leveling up" and traditional fantasy themes usually seen in RPGs with turn-based strategy. If you play games like CIV for the battles, you'll really like this game a lot. It's all battle strategy.

You use units (varied, all from traditional fantasy) and move them around in a similar fashion to board games like Risk or Axis and Allies. Of course, these are much more sophisticated, akin to CIV, where each unit has different strengths and weaknesses, impact on other units, skills, movement points, etc.

Best of all, you can "level up" characters to a certain degree, and keep them from one board to the next within a campaign. It's rich and robust. I can't believe gameplay this good is available free.