Aim - to put the 12 Pentominoes in the selected area. These are the unique shapes made up of five regular squares - defined originally by Solomon W Golomb in 1953 - and feature in Arthur C Clarke's book Imperial Earth.
You specify how many solutions to search for - by default 1. Note this can take time.
If 1 solution : press ShowMoves to see how it is solved - using backtracking - where the program tries to place a pentomino in the next free position, and if successful tries to place the next position. If it cant find a place the current choice must be wrong so another is sought.
If many solutions - press ShowSolns to see them.
You can select different areas of 60 squares to fill.