We have some ideas …
One would be interesting to system Necessity such as:
Hunger: Eat something (some foods are poisonous)
sleep: Resting somewhere or log out.
Pooping / Pee: Anywhere or Toilet. (could be placed to facilitate a blur with animation or just a blur)
Wash: On the river, sea, lake, waterfall or shower.
And some other needs like a special need for each race as:
Aquatic race: swimming / diving for a while.
Hunter race: hunt certain number of monsters.
Miner: gathering Some materials and/or seling
Builder: building / getting near the buildings themselves.
and things in this line of thought …
Not meeting your needs:
Hunger: death
Sleep: Debuffs as slow.
pooping / peeing: pee / poop in his pants = stench, poor hygiene, attract insects / animals and diseases
Wash: even poop / pee
Another idea would be: pooping animals
Animals that eat grass just poop poop.
the poop would last a while, could they attract certain animals that would eat some of them like player poop.
Some animals would eat plants / minerals from their natural biome and defecate special / rare minerals. these animals could be tamed to produce these minerals on the farm by planting your own food and feeding him.
Larger animals like titans could also eat some of its biome and defecate rare minerals. this would cause some players do not kill the titan but try to pick up these minerals.
some plants could also produce rare minerals/fruits . these plants may be planted too.
These minerals / food " organic " could be dropped by plants / animals and stolen by other players. it instigate the creation of more developed and protected farms and increase the diversity of ways to acquire these materials.
That would make the game more difficult, interesting and stimulate agriculture, livestock and trade.
sorry for bad english