Game Development Reference
“But what about virality? Isn't that the whole reason we're making a social
game?” Well, yes. Social games do get a nice lift from virality, as we saw in the
earlier ARM funnel image. The specifics tend to be heavily influenced by the
mechanics and users of the social network on which the game is played, and
those elements, more than most, evolve and change over time. For example,
Facebook now exercises much tighter control over game spam than in previous
years. Although this is great for users who got tired of hearing about the lonely
sheep that wandered into their friend's newsfeed, it isn't as great for social
game designers, who now must pay to get eyes on their ads—eyes they used
to be able to attract for free. Other social networks like Xbox Live!, Steam, and
Game Center don't really do much to help with virality either; at best, users are
able to compare achievements or see what their friends have recently played.
Beyond that, it is up the user's individual power to attract their friends if their
choices have a chance of going “viral.”
As we discussed earlier, virality on games—and on Facebook games in par-
ticular—is now trending to around 0.5, meaning that for every two new users,
you're likely to get one additional, based on players opting in to common in-game
prompts to send out messages to friends. This value is called the viral coefficient.
You can measure the virality of a product by looking at its viral coefficient.
This is a measure of both popularity and growth. The number should give you
insight into how many additional new users each new user will attract. The
common formula used to calculate this factor is:
X numberoffriends each person invites
of those friendswho accept theinvitation)
Generally speaking, if the result is 1, the application is experiencing linear
growth. If the result is greater than 1, the popularity of the application is rising.
If the result is less than 1, the application is falling in popularity. This num-
ber can be a useful measure of user engagement and the overall quality of the
design of a game. Understanding this value can inform the amount of money
you want to spend on advertising and act as a general health index for a game.
The good news is that every one of these additional new users gained through
virality is effectively free. This is one reason it is so important to build game
mechanics that encourage users to invite their friends to play. Even if you end up
having to incentivize users with in-game goods or virtual currency, as long as the
value of the incentive is cheaper than the game's then-current CPI, the in-game
attraction is cheaper than having to purchase advertising to attract a new user.
And because each of the new users attracted in this fashion will, in turn,
attract more users themselves (hopefully), virality remains a strong force for
social games, even in ecosystems where the network itself tends to tamp down