The "Giant Puzzle" was first introduced in 1888 by McLoughlin Bros of New York. We found a picture of the old puzzle in Slocum and Botermans book, "New Book of Puzzles" (1992) and were fascinated by it. It has a bit of a Sukoku edge to it, and its really hard.From our shop and all high quality hardwood construction. Its quite a beautiful puzzle to look at. We kept the orignal name: "The Giant Puzzle" but its not giant sized, measuring about 5.5" x 5.5" x 1.25". Ergonomically its terrific to handle.It has 25 pieces in the base. Each piece is different. There of 5 pcs of each color. The the numbers 1, 3, 5, 7,,and 9 are also printed on the handles of each color (thus, there will be a blue-1, blue-3, blue-5, blue-7, blue-9, and then likewise for each color). The handles are a nice feature of this puzzle which we added from the original design which just had flat blocks which we found very awkward to get in and out of the puzzle.The object is to arrange all the pcs in the base such that there is no color repeated on any row, column, or any diagonal. Also, no number can be repeated on any row, column or any diagonal. Also, each row, column and major diagonal must add to 25. To tackle easier tasks to warm your brain up, you might try to tackle each of the requirements separately (that is, just work on colors, or just work on numbers, or just work the 25 addition) before you take on the full challenge of making them all happen at once!This terrific puzzle is very challenging and will highly appeal to the person who enjoys Sudoku or enjoys logic puzzles.