Pegraph
Pegraph is a puzzle app for the iPhone. Pegraph is free and I currently have no intention of ever charging for it.
Pegraph is a combination of sliding-block and planar-graph puzzles.
Some of the tiles have pegs and lines connect the pegs. Your aim is to move the blocks around until none of the lines cross and no line runs through a peg.
Lines that are crossing are shown in red and so are bad pegs. Good lines and good pegs are blue. Turn all the lines and pegs blue.
The resulting set of lines is called a “planar graph”.
Other planar graph puzzles are available, so why make a new one? Planar graph puzzles are easy to solve. Once you’ve worked out the method, it becomes a mechanical chore. Making it into a sliding-block puzzle means that you must think much harder, even for very simple graphs.
You can download a free Windows version of Pegraph from
http://www.peterbalch.btinternet.co.uk/Pegraph.htm
