Abandoned School Escape

You left town at about seven years old. Your father had to transfer to another branch of his company. So you and your mother tagged along. However, you did not leave the town without any memories of it. You used to hang out near the school everyday. You and your friends would run around the play ground and wait for the others after school. Your best friend is also from that school and you promised never to leave each other. But you broke your promise first and you felt so bad. So after almost twenty years, you decided to visit your old town hoping to relive the moments you had there especially in your school. However, when you arrived there, the school is already abandoned. Still, you want to have a look around so you entered and explored the place. It seems like it doesn't want you to leave.