Character is controlled with the mouse and the keys W, S, A and D. "WASD" moves the character and mouse movement gives a course to this movement. In the middle of the screen you will notice a small reticule, which targets enemies, friends, and various objects.
If you need to use normal mouse cursor from time to time (to select an item from the quick menu for example) switch to the normal mouse pointer by pressing the Alt key, this will make the screen darken and you will be able to use the mouse in normal way (the same happens when you open any dialog box with keyboard shortcut). Pressing the Alt key will return to the "targeting" mode.
Important keybindings (default configuration):
Moves the character
Class specific mechanic
Quick use items
Class specific Tactic skill (like dodge, sprint, block)
Interaction with various objects and NPC
Holding it will lock on target
Quest path toggle
Quest log and achievements
Your hero, his sills, companions
Inspect mode allowing you to hide HUD and zoom in/out with mouse wheel