Simplify the following text for a Grade 5 native English-speaking person.
Original: Pack-in games are intended to be system-selling games that make good use of the positive features of a given system . Sometimes a pack-in game will be changed to a more popular game , or another game will be added , along with the original pack-in , if it is perceived that a newer game will sell more systems .
Simplified: They are often in the same box as the game system , which is why they are called pack-in games .