On a Sunday, you agreed with a group of friends that in the afternoon you would see each other around the city, eat a pizza, and tell stories. With nothing to do, you arrived earlier than the appointed time. Walking around the fortress, you noticed some stairs leading down to a door that said ENTER AT YOUR OWN RISK! You've been to this fortress countless times before, but you don't remember seeing this door before. Bored and curious at the same time, you tried the door and to your surprise, it was open! You walked in, and the next second the door closed behind you! You tried to open it but to no avail. Solve puzzles, explore the area, and find hidden gems at your own pace. Try a new type of experience with your smartphone, the perfect mix between a walking tour, sightseeing, and a scavenger hunt.