Every Cube World day, new Missions become available. Missions send players to Dungeons or against Bosses. Completing a Mission gives valuable rewards such as Weapons, Armor, Cubes and Platinum Coins.
Missions are obtained by speaking with NPCs and are currently either straightforward killing or artifact quests. Fulfilling quests will result in gaining Experience as well as material rewards like mentioned above.
As of now, Wollay has stated that he has suspended Quests until he feels he can implement them better.
Preview screenshot of a mission log