In the previous post I discussed the fact that addiction and enjoyment are not the same thing, and I cited several games who have the addiction (if not also the enjoyment) down square.  What I did not talk about is how exactly you go about making that happen.

Casinos have boiled one technique down to a fine art: high payout at rare intervals.  Now it’s not simply enough to randomly dole out a large reward on an arbitrary basis.  Players need to understand why they’re getting this reward, even if there’s a lot of randomness to it, it must be as a direct result of an action they took.  The reward happens to also provide a fun element, but much as Crack is is much more addictive than its more expensive counterpart Cocaine.  Because the high is so intense, and so short-lived, it triggers an extreme desire to repeat activities that led to the high in the first place.

Examples:

• Any form of Gambling, Poker, Blackjack, Slots causes you to win big only occasionally, which keeps you playing another hand or pulling the lever one more time, just in case you get lucky again.
• Match 3 games implement this by having a normal scenario be the matching of three items causing a chain of new blocks to drop.  Occasionally the blocks that drop will cause a further match, and a cascade effect may occur giving the player massive point multipliers.  This is random to a certain extent because the player is unaware of what blocks will drop next.
• Diablo/World of Warcraft acts through rare item drops.  Players will do a raid dungeon over and over again on the pure hope that an extremely powerful and rare item will drop that they may be able to obtain.  Even if a usable item does drop, there is not a guarantee that the individual player will be the one to roll for it.
• Crack Cocaine works by releasing massive amounts of Dopamine into the brain.  This high only lasts a short time, and repeated hits will not achieve the same level of euphoria as the first round did.
• In experiments with mice, a mouse will spend proporionally more time pushing a button which dispenses food at random intervals than with a button that dispenses food at regular intervals (say every ten pushes of the button).  This effect is so pronounced that a mouse will spend the majority of their life tapping away at the button given the opportunity.  If the reward is of higher value than food (a non-narcotic drug), the effect magnifies).