Basics

Movement
The W and S keys allow you to move foward/back, while A and D turn you left/right. Q and E keys allow you to strafe left/right.
F11 allows you to go fullscreen if the game hadn't done so so automatically. These controls are not set in stone and can be modified in Options > Controls

You can also modify what key will target the next enemy, auto run, loot, etc.

Game controls, you may adjust to your style as needed

Non Playable Character

There are as many allies as there are foes and friendly npcs cannot be attacked. Some of these npcs give you quests while others only exist to converse with. Some npcs may even be merchants selling gear or important quest items. Hostile npcs exist only to be slain and will generally attack when you are near them.

To interact with friendly npcs, you must click on them while being close enough. If you're too far away from the npc you'll only see their status bar. Hostile enemies usually target you first, which will automatically let you see their status bar. If you want to check an enemy without engaging in battle, click on them from afar

Combat
Combat is in real time and the enemy will not wait to attack. Your abilities are placed on the left hot bar and you can either click the button or press the related number key to attack. Each class has their own set of skills and require a certain amount of rage/mana to cast. You must be close enough to the target to activate the skill and has a specified range