The Koa wear blue and white floral board shorts (Hawaiian shorts) and tan headbands with matching armbands. They go shirtless and barefoot. They have tanned skin and black hair. Their AI is very complex, thus making them much more advanced than your average NPC's. Their villages made of Thatch and Bamboo chunks make for a very tropical looking area.
The Koa prefer living on stilted villages over coastal waters, constructing their villages from wood and bamboo. The Koa are a communistic society - they share all that they have with any member in need. If a Koa is hungry, his neighbor will give him food. The harvests of the fishermen are stored together in a communal chest for the village to share.
Each Koa has a job to do to support the community. So far three jobs have been revealed: fishing, hunting and trading.
Hunters go out of the village to fight off monsters to protect their village. They are equipped with two weapons: a ranged weapon and a melee weapon. Their ranged weapon is a leafy dirt ball that is thrown at their foes. This leaf ball does 1 heart damage. Their melee weapon, which does two hearts of damage, is called a Dagger. When a hunter encounters a threat, that hunter will call out to alert other hunters of the threat. Koa will respond to the call if they are in good health and believe they have enough hunters to prevail. Injured hunters will flee from battle until they have gathered enough strength to fight again.
Fishermen spend their time in their village fishing to feed their village. Fishermen eat what they catch and turn in everything else to the communal chest, so hunters will have something to eat as well. Unlike the hunters, fishermen will not fight off threats and will instead flee fast.
The Koa will be passive towards the Player, and only attack if one of two events happens. One, if the player attacks a Koa. If this happens, the attacked Koa will hit the player once with a leaf ball and forget about the incident. Second, if the player kills a Koa, all the Hunters will attack the player. Worse, they will never forgive you for your horrendous crime, and you can never come to the village again, even on Creative Mode. They do not mind if you take fish from their chests, and the Fishermen will always renew the supply of fish, making the Koas effective food sources.
Lead AI developer Corosus has given the Koa the ability to trade. The trading begins with a Koa saying "Hello!" in the Hawaiian language; "Aloha!". You switch to an item you want to trade with them. The item they are holding is the one they are trading, i.e. a scale helm. They will say something in either red, or white. When they accept a trade, (saying a word in white) you right click the Koa, and you have traded items. The item traded will now be in your inventory. If they say a word in red, they have rejected your item, but you can switch to another item. You can walk away at any time. They have a fascination with shells, which can be obtained by putting sand in a sifter, and pearls, which can be crafted from certain shells.and they are wery hard to find on 1.4.7. IMPORTANT NOTICE: As of version v5, this trading system if now different. Koa trading plates are now used instead of this. Do not think that this is a bug or glitch and thinking you must change the config. One specialized person will spawn near Koa trading plates. You can identify them because they wear orange shorts. This actually makes 3 specialized jobs.
The Koa AI utilizes an ingenious design that both minimizes computational time and allows them to pick paths in a more human-like manner. Instead of calculating the best path from their current location to their destination (taking lots of computer processing for distant locations), they instead calculate a path towards a nearer point in the general direction of their destination. In this way entire paths don't have to be recalculated every time a dangerous group of monsters is encountered or some blocks along the course of their path have been modified. Its is also noted that they can jump one block out of the water instead of the usual half-step.
The Koa have their own rituals that they practice during night, like the "Drums Festival" where all the Koa go to the drum area to dance and play the drums, the "Drum Bonfire" where the Koas go arround the main bonfire, sit and here the music of a member using drums and the "Bonfire Ritual" where the members sit arround the main bonfire and sometimes a member stay up like if was saying something. (reported by a player in survival mode that even tried to participate of the rituals)
The Koa have the sound of Zombies when they get hurt.