Games have a tendancy to drain battery power, especially on laptops and phones. They use most of the CPU and ressources. And since some games can be extremelly addicting, you may not see the time pass and unintentionally drain all the battery in a matter of hours.
Games have found a way for you to monitor your battery level while still having fun. Usually found at the top of the screen, your laptop's battery is shown for you to keep an eye on it. Many Iphone games do this too, giving you information about your current battery life and your network coverage.
Some games, such as Kane and Lynch 2
, show a fake battery meter to simulate a camera view. The battery meter also shows up in movies such as Cloverfield and the REC franchise.