In the medieval times, villagers used to build fortresses in order to protect their kingdom. One of this fortresses is the Akershus Fortress. During your trip to Oslo you could miss visiting it, as it's one of the main attractions of the city. Even if it was built during the medieval times, it's still in very good conditions and got your full attention. But your visit to the fortress got longer than you expected and it has been closed. As there is nothing inside which can be stolen, there is no guard during the night. So you are trapped inside alone without any help. You will have to explore and find a way out. Best of luck!
Walkthrough for Escape from Akershus Fortress