Nearly every action (or lack thereof) affects how the player is judged by their followers: the player may be seen as a good god, an evil one, or in-between the two. The land, interface (including the hand), and music change according to that alignment. A good god's temple is brightly coloured, while an evil god's is designed to look intimidating. It is not necessary to consistently perform acts of either alignment and a mixture of the two can be used to stay neutral. The player has two advisors, one good and the other evil, who try to persuade the player to do things according to their alignment.
An important task is expanding the villages, by constructing buildings and increasing the number of villagers. Important buildings include houses, the Village Centre (which displays the god who controls the village and the available miracles), and the Village Store (which stores resources and displays the villagers' desires). Buildings are created in the Workshop after obtaining blueprints. Wonders are special buildings granting a specific benefit. Villagers belong to one of eight tribes, such as Norse, Celtic, or Japanese, each having a different Wonder. Villagers can be assigned to perform a specific task such as fishing or starting a family. If the Temple is destroyed, the game is lost. When attacked, Temples transfer damage to their god's buildings and followers in defence; only Temples whose god has no followers are vulnerable.
The Temple is surrounded by sites where villagers worship, generating the power needed to cast miracles. Villagers require feeding, healing or rest to worship. How many villagers worship is controlled at the Village Centre, and which miracles are available depends on those available at the player's villages. Miracles include providing food or wood, healing people, and providing shields to protect an area. Miracles can also be cast by using Miracle Dispensers, a common reward for completing Silver Reward Scrolls. These allow the casting of a miracle without worship. Miracles can only be cast, and most other actions performed, within the player's area of influence, which can be extended by expanding the population of villages owned, or by taking over others. Miracles can be selected at the Temple or Village Centre, or by performing certain gestures with the Hand. Power can also be produced by sacrificing living beings at the altar.
The general goal of a level is to gain control over every village on an island, accomplished through acts that persuade the villagers to believe in the player. Villagers can be swayed by everything from assistance with day-to-day tasks to being terrorised by fireballs and lightning storms. Artefacts (special objects that glow in their owner's colour) and missionary disciples can be used to impress villagers. Villagers become bored with repetitive attempts to impress them. For example, if boulders fly overhead too frequently, their effect is lost. This forces the player to use multiple methods to convert a village.
The game features a skirmish mode, where other gods are battled for control of an island, a multiplayer mode over a local area network (LAN) or an online service, and The God's Playground, where gameplay aspects can be practised. In multiplayer mode, deathmatch and cooperative modes are available. In cooperative mode, players share a creature. Black & White includes a feature enabling the import of real weather.
Creature
One of Black & White's core features is the interaction between the player and an avatar- like creature. Three are available to select from the beginning of the game and others can be obtained by completing Silver Reward Scrolls. The currently-owned creature can be swapped with a new one at certain points in the game. The creature starts out small, and grows as the game progresses. Each has strengths and weaknesses: apes are intelligent and proficient at learning but lack strength; tigers are strong but learn slowly.
As a god, the player can teach their creature to perform tasks such as stocking the village store or performing miracles. The creature is taught what and when to eat, and how to attack or impress enemy villages. Fighting skills may be taught in one-on-one battles with other creatures; attack and defence abilities can be improved. Teaching is performed using a reinforcement learning system: if the creature does something the player does not want, it can be discouraged with a slap. If the creature does something the player approves of, it can be stroked. The creature remembers the response to various actions and gradually changes its behaviour accordingly. With time and repetition, it can perform complex functions that allow it to serve as the player's avatar. Three types of leashes are used to command the creature to go to a specific place, and can be tied to a building to restrict movement. One leash encourages the creature to pay attention when actions are demonstrated; the others encourage either benevolent or malevolent behaviour. The game reinforces the creature's choices and learning by providing visual feedback, and the creature has an alignment separate from the player's. Evil wolves sport glowing eyes and large fangs and claws; good ones turn a shade of purple and glow gently.
Lionhead Studios used Michael Bratman's belief–desire–intention model to simulate creatures' learning and decision making processes. A creature forms an intention by combining desires, opinions, and beliefs. Beliefs are attributed to lists that store data about various world objects. Desires are goals the creature wants to fulfill, expressed as simplified perceptrons. Opinions describe ways of satisfying a desire using decision trees. For each desire, the creature selects the belief with the best opinion, thus forming an intention or goal.
