Why not try a Murder Mystery?
But if you want something different, why dont you try A murder mystery trail. Download at a reasonable cost from treasuretrails.co.uk, follow the clues, solve the mystery, it a fun activity for all ages, with a walk included.
For adults and children alike, the treasure map, is a who done it which takes you on an easy route in the Park, solving the clues. Really good fun. Its a circular walk, only about one and half miles.