When Space Invaders was launched, it was all about getting that high score and trying to develop a strategy on how to avoid the falling missiles. Even though it was a simple game, the need to achieve and exploration of a new digital world are what kept individuals playing for hours and hours at a time.
But then, the game got harder. The aliens began moving faster and got closer together, forcing the gamer to adapt and keep coming up with new strategies for success. The game allowed a new world for the curious mind to explore, test, and conquer.
Similarly, in the game Missile Command, the player is trying to save a group of cities and protect them. Each level gets harder and more difficult and the strategy changes. The left and right missile bases shoot slower than the middle missile base, so the player uses the left and right missile bases to fire a wall of defensive artillery to destroy the first wave of incoming nuclear missiles. The center missile base is used to defend against faster moving bombs and weapons. As the player achieves new levels, it becomes more difficult to predict how the enemy will attack.
These types of strategies in basic games make it very enticing – the more complex the game gets, the more and more addictive it gets. As the digital world increases in complexity, the curious gamer becomes more immersed and eventually becomes hooked. Looking at modern games like the World of Warcraft or other massive multiplayer online role-playing games (MMORPGs), the sense of curiosity is fulfilled because players are exploring new lands and new worlds. These MMORPGs are video games on steroids. With online games, players are exploring with other people around the world. The social element of online games magnifies the addictive nature of video games. New dungeons and quests offer new creatures with magical weapons or armor that characters can use, making it not only challenging, but rewarding experience for the player. These types of digital rewards signal the body to release endorphins into the bloodstream and feel-good dopamine into the brain. It tells the player “this is fun” and keeps them hooked into playing more and more.
Here is an older BBC documentary on a kid who played thirty hours a week of video games. Note that this behavioral addiction affected the kid's attitude and life.