I tried it at a friend's house. It plays much like Pikmin, only you are an evil bastard that has some magic and a dark castle/tower in some hellish-like place(seemed like a volcano, though I only spent 10 minutes there at most). The idea is to conquer or destroy anything that comes in your path. You can make yourself be renown by destroying things and cities or by dominating them, making them your slaves and so on.
You use "minions" for that, and they come in different colors, each having a specific available action:
Brown: They are melee units. They can ride wolves if you come across some and tame them. The most basic of all units.
Red: Think a pyromaniac. They throw small molotovs at things(making them ranged), and are the only way to get past flammable things that you can't break with your weapon
There's also Green and Blue, but I didn't come across any during my short playtime. Also, magic and minions aside, you can also attack with a weapon of your own and upgrade your armor in your castle. I've seen swords, axes and maces, though I think my friend mentioned more types.
And for those interested, you can also have your own maiden. A dark maiden. Someone just as sadistic as you(the Overlord) are.
Oh, I forgot. Those screens that Raks posted are from the game's prologue, during which you are, obviously, a small kid. You also have some sort of gorilla/yeti for a friend, after a small event in the prologue. He is captured once in the main game, and I'm not sure whether you get to use him per se once you're an adult, but he's there. And he breaks entire soldier squads like they are nothing.