Exactly how many bullets can kill a person? How many apples can one man carry? In real life, the answers vary. In a video game, real life must be explained in numbers. That includes religion: how it spreads, who believes.

A couple of weeks ago, while I was pondering some of video games' unusual intersections with the divine — they allow, for example, millions of people to pretend to be God — I became curious how religion was programmed into games. I wanted to know how video game creators determine how to make faith, the very thing that depends on an acceptance of the unspecific, into a system of numbers, the very thing that makes a video game run.

How does a video game designer making a game that has religion decide how many people must believe in Jesus Christ before Christianity catches on?

How do they determine when a community will lose faith or gain it?

How do they know the ways in which Judaism would intersect with Islam, not in the real world but in a world that is entirely digital, determined by numerical systems and influenced by the stirring hand of a video game player?


How do they calculate the benefits a society would gain by being Buddhist?

The creators of the best-selling video game series Civilization dealt with some of those questions in Civilization IV. The 2005 computer game was the first in its line of world-history-constructing games to include real faiths and a system of religious belief amid such series-standard systems as science, exploration, economy, agriculture and warfare. The game lets the player sculpt the history of a civilization, starting with settlers on an ancient plot of land and making a game out of the advancement and expansion of that community's knowledge, terrain and ambitions. A society's attitudes about religion would now be a part of that.


Approaching the game's lead designer, Soren Johnson, who has left the Civilization series and now works at Electronic Arts, I asked a simpler question than the ones above: How do you turn religion into a system inside a video game?

I could have phrased it two other ways: How do you establish the physics of faith? And... How do you make religion entertaining and indisputably worthwhile?

The answer I received benefits from minimal interruption. Here is Soren Johnson, explaining how religion became a part of his last video game. How it worked and how it benefited the virtual world:


A History Of Turning Life Into Numbers

"The Civilization series has a tradition of boiling complex ideas down to simple rules and numbers. For example, the history of scientific discovery becomes a graph-based technology tree and a series of bars to fill with the beakers. Once a civilization's cities create enough beakers, Writing is discovered, which then allows the player to begin researching Alphabet. In Civ4, we decided to finally 'name names' with religions and put them directly into the game."

Seven Religions Make The Cut

"First, we narrowed down the major world religions to the seven that would resonate most with our audience (Judaism, Christianity, Islam, Hinduism, Buddhism, Confucianism, and Taoism). Then, we associated each religion with a single technology (Hinduism is linked to Polytheism, for instance), so that the first civilization to discover that technology would also become the founder of that religion. Furthermore, a random city inside that civilization (while weighing populous cities higher) would become the Holy City for that new religion, which would allow that city to eventually hold a powerful unique building for that religion (such as the Temple of Solomon for Judaism). This Holy City becomes the first city in the world to contain that religion, represented in [the game's programming] code as a simple boolean value (either a city contains a specific religion or it does not)."



How A Computer Spreads Hinduism From Berlin To Paris

"Religion can then spread from that first city in one of two ways, either passively or actively. Passive growth happens naturally, based on proximity, cultural connections, and trade routes. In other words, if Hinduism starts in Berlin, it might quickly spread to Munich and Frankfurt as they are nearby cities with similar cultures. Further, Hinduism might also spread quickly to Paris as France and Germany have active trade networks, with both land and sea routes connecting Paris to Berlin. Furthermore, once religion spreads to a new city, that city in turn acts as a new source for spreading that religion passively to its own neighboring cities."


"Internally, the game is simply rolling a dice every turn to see if each religion has spread to a new city, with the odds increasing based off of the connections already mentioned. However, one other factor lowers the odds of a religion spreading — the presence of other religions already in that city. Thus, if Paris was already Buddhist and Christian, the odds of Hinduism spreading to it go down significantly. As more and more religions spread to a city, the odds effectively go down to 0, so that no city will ever naturally have all seven major world religion through passive growth."

Time To Press The "Spread Religion" Button

"Civilizations can also spread religion actively by building Missionary units, moving them to other cities and then triggering the Spread Religion action. This action consumes the unit but with a X% chance of spreading the religion to the new city. If the city is without any other religions, the odds are 100%, but they go down a little with each other religion already present in the city. The Missionary unit was an important development in the design of the game. The unit was not part of the initial design, but it gave players the crucial ability to control the spread of religion. Before, players were often frustrated with the 'black box' mechanics that determined how religion spread passively. With these two systems coexisting, players could decide for themselves how involved to become in the religious part of the game while still ensuring that world religions would eventually fill up the map."


The Three Benefits Of Religion (In Video Games)

"The actual gameplay benefits of religion took a long time to balance, but in the final release, religion affects the game in three ways: buildings, civics, and diplomacy. Furthermore, civilizations have an option to choose a single State Religion, which modifies how these systems work.


"First, the presence of religion in a city unlocks a number of new buildings to construct. For example, a city with Christianity can now build a Christian Monastery (creates culture and science; allows training of Christian Missionaries) and a Christian Temple (creates happiness and culture; citizens can work as Priests). For every three Christian Temples in one's civilization, the player can also build a Christian Cathedral (more culture and Priests; extra happiness if Christianity is the State Religion). Finally, the Christian Holy City can potentially build the Church of the Nativity, which creates one gold per turn for every city in the world with Christianity - thus giving the player a strong incentive to spread Christianity far and wide.


"Civ4's civics system allows the player to define his own style of government by selecting a single option in a number of categories. For the category of Religion, the game gave the player four choices:

- Organized Religion (can train Missionaries without Monasteries; cities with State Religion construct buildings faster)
- Theocracy (new military units receive +2 experience points in cities with State Religion; only State Religion can spread passively)
- Pacifism (double Great Person birth rate in cities with State Religion; extra support costs for military units)
- Free Religion (no State Religion; +1 happiness per religion in each city; extra science)


"Finally, a civilization's choice of State Religion greatly impacts diplomatic relations - how the AI-controlled leaders perceive the player and each other. For example, two civilizations both with Buddhism as the State Religion will naturally have good relations between them. On the other hand, if the player chose Judaism as the State Religion while her neighbor, Saladin, remains Christian, relations will be strained. Indeed, Saladin might demand that the player abandon Judaism and adopt Christianity a number of times, and each time the player refuses, she will suffer a diplomatic penalty with Saladin. This system forces the player to make a tough choice when choosing a State Religion: Should she take the religion which provides the most internal benefits (extra happiness, for example) or choose the religion which will assuage a dangerous neighbor?"


Thanks again to Soren Johnson for all of that rich detail.

In the real world, believers just believe. Numbers may determine how strong Hinduism is. Maybe there's a way to quantify the benefits of Taoism or the impressiveness of someone who proselytizes a faith. Maybe; maybe not. But in at least one game you could. In at least one game, religion counted. It was a system, briefly demystified, briefly revealed.


[Lead PIC via Flickr]