This is a wonderful puzzle which requires a person to think in three
dimensions. Most people seem to find it easier (and more fun) to start by
working with physical pieces on a grid. I’ve introduced it to classes as
young as grade 5, and to individual students younger than that.
I’ll post more 5x5 puzzles soon!
You will find many puzzles of varying sizes and degrees of difficulty at Simon
and at BrainBashers
also a commercial version called “Utopia”.