is a complex and sometimes team-oriented procedure. The player must first locate the desired materials using prospecting skills, as resources give no visible sign of their presence. If he does not have teammates to aid him, he may need to balance his work between extracting the resource and treating the extraction site to prevent it from collapsing prematurely or exploding. The site's location and the harvester's own skill levels both affect the maximum possible quality of the extracted resource. Player vs. player In general, player characters are not allowed to attack other player characters or peaceful non-player characters. The exception is specifically marked zones, either smaller areas, like the PvP arena in the starting region, or larger regions, like the "Prime Roots" of Atys. It is also possible to engage other players in one-on-one combat (duels), this requires acceptance by both combatants. Game world The game takes place on the planet Atys. Unlike normal planets, Atys is an enormous tree large enough to sustain an atmosphere and multiple ecosystems on its surface and within immense networks of branches and roots. The various creatures in Ryzom have differing AI based upon their species that allows them to perform many realistic behaviors, such as migration and movement as a herd. Carnivores, for example, will attack specific animals for food, and certain animals hunt in packs. The game also features changing seasons and weather. Weather effects include rain, snow, and wind. Tied to the season and weather changes are the movements of animals and the availability of harvestable materials. For example, a certain type of sap may only be harvested during spring rains and be unattainable during other seasons or weather conditions. Weather conditions can change minute by minute. Each game season (spring, summer, fall, and winter) lasts four real-time days. Player characters come from one of four distinct humanoid races, collectively called "homins". The 'Matis' are a proud and noble race of forest dwellers. They have mastered the art that is a fusion of botany and genetic manipulation, and consequently they have constructed their kingdom and castles from massive trees grown for that very purpose. The 'Tryker' are a fiercely independent and fun-loving race of lake dwellers. They build large floating cities on their lakes, and networks of wind-powered water pumps around them. The 'Zoraï' are a spiritual and tranquil race of jungle dwellers. They build their temple-cities within naturally fortified areas