A lot of games build in rewards to make games more addictive, for example on PS you get achievements if say you play for 100 hours, or in other games if you beat a level you get a new weapon or power. When this happens your brain releases dopamine, a motivation chemical. The game is designed so that you want more dopamine so you play longer! Games get more addictive the more that game designers understand the effects on your brain. If you’ve ever played a game for a long time, you might notice that the rewards get harder and harder to get. This is to keep your brain hungry for dopamine and to keep you playing!