I made up this game 30 minutes before youth group. It requires very little supplies and set-up. It is a great game to play in a building with many rooms and cabinets to hide things.
Take a teddy bear (or any stuffed animal, or any object you want, really) and have one person hide it, while the rest of the group waits in another room where they can’t see the person hiding the teddy bear. When the bear is hidden, unleash the students to find that teddy. I say if a student finds it in less than 2 minutes, they get a cool prize like a 2-liter bottle of soda. Between 2-5 minutes, an energy drink. After 5 minutes, maybe they get a candy bar or something. It is easy and everyone can play it!