Portal Knights

Portal Knights is a 3-dimensional adventure sandbox RPG developed by 505 Games. It has 3 character classes: Warrior, Mage, and Ranger. After you selected one, you can further customize its appearance. There are a lot of randomly-generated worlds (also known as 'islands') plagued by the Hollow King you're set to defeat. You can travel between islands by portals. You gain points and unlock new skills for your character with each completed quest. You need to apply tactical thinking to overcome enemies as it's crucial to find their weaknesses first and then choose the appropriate spell or weapon to crush them. Portal Knights can be played in co-op mode together with 3 additional players or 2-player split-screen mode. You can unearth hidden islands, inspect their biomes and dungeons and find rare gems and supplies. Pick one island and transform it into a piece of art by building absolutely anything using a wide variety of construction materials. Your creations can be shared via Steam Workshop to critical acclaim!