Underworld was one of the first games to offer genuine real-time 3D movement and combat, as well as mouse control for changing the view. Thing is, it's not the now-standard mouse-look model. Instead, you click near the edges of the screen to rotate your view, and near the middle to move forwards. It's like Dungeon Master but in real time. And to complicate things, you have to click icons at the side of the screen to choose how to interact with the 3D view: Examine, Use, Pick Up, Talk and so on.