Behind the scenes, your favorite video game is probably playing you. The smartest game developers know exactly what makes us tick and use that to insure that we stay locked into their games for as long as possible. While games need to be fun, there are also a host of psychological tricks video games use to keep players in front of the screen.
Some games scatter hidden collectibles all across their worlds, whereas others include secret alternative paths for players who enjoy seeing how much they can cheat the system. Then there are free-to-play games, which take psychological manipulation to new heights so that players spend real money on digital goodies. When you think back on the best video games, chances are you'll recognize a few of the tricks developers used to keep you playing.
One of the best ways to keep gamers playing is to dole out a steady stream of rewards. Whenever a player fulfills the necessary requirements for a game's contingency (or guidelines for success), they should receive some type of tangible feedback. This feedback can take on all sorts of forms including Grand Theft Auto gradually increasing a player's wanted level to gaining a higher rank and receiving a new gun in Call of Duty's online mode.
This type of response conditioning dates back to the work of behavioral psychologist B. F. Skinner, who performed experiments on rats in the 1930s. Skinner noted that his rats would continue to repeat the actions that garnered them the best rewards. Humans are equally capable of being conditioned through positive reinforcement, which makes it easy for game designers to keep us chasing that next big in-game upgrade.
John Hopson of Gamasutra uses the term "variable ratio schedules" to explain how often different pieces of loot appear in games. According to Hopson, every collectible item in a game has "a specific number of actions... required [to produce a drop], but that number changes every time," which makes some items appear less frequently than others.
Studies have shown that games that employ variable ratio schedules typically yield higher play times, as the lack of predictability makes the experience feel less predetermined, and potentially extends the amount of time it takes a player to collect everything they want. After all, there's nothing more satisfying then stumbling upon a super rare shiny Pokémon after wandering through the grass for several hours.
The entire practice of collecting — whether it be Beanie Babies, Pokémon cards, or agility orbs in Crackdown — is driven by an evolutionary need to gather and horde goods. Historically, these urges were based around the need for sustenance, and can be seen in hunter/gatherer societies. As humanity has evolved, that urgent need to collect still exists within us, even if our physical needs are being met.
Video game developers take advantage of that by offering a bevy of virtual goods to collect within their games.
The unwritten rule of video games requires sequels to double down on every facet that made the original entry so successful. If the first Borderlands has several hundred thousand guns, the sequel needs to feature some 18 million. If there are four special zombies in the original Left 4 Dead, then you'd better believe there are eight in Left 4 Dead 2.
Pulling this off sometimes requires a suspension of disbelief, especially when a prequel comes out part-way through a series. The official reason why Batman has the more gadgets in the Arkham Origins prequel than he does the rest of the series is that he always had them, but chose not to use them in the prior games that take place after Origins.