Overlord is a somewhat novel mix of action and strategy, not turn-based but direct-control. A bit fiddly at start but offers the posibility to JUST SWARM THEM WITH BROWN MINIONS; MUHAHAHAH! Sorry, got a bit intense there.
Seriously, this game comes with a nice story, putting you in charge of everthing that is evil and devilshly bad in fantasy worlds, FINALLY THE ELVES WILL PAY FOR THEIR INSULTING BEAUTY! Not sure where that came from.
If you can deal with the controls and a ending that drags a bit, you will be rewarded with a still nice to look at game and your own seat on the throne. MAKE THE HALFLINGS PAY WITH THEIRS LIFES!!

My review extends in the same manner to Overlord 2 and the addon Rising Hell. You should keep your distance from the heresy that is The Fellowship of Evil Spin-off.