One Photo Out of a Sequence of Many
As an interesting challenge.
Have a sequence of photos with a logical connection to one another (a theme, a story, etc.), that are displayed in a way that creates a mega photo when looked on from a distance. In the mega photo, each element is one of the pictures in the sequence. It is similar to using a lot of photos to create a larger one, but here all of the photos used should have a uniting theme and preferably their sequence should also make sense.