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Invented by McLoughlin Bros in 1888 and later published in the "New Book of Puzzles" by Jerry Slocum and Jack Botermans in 1992, the Giant Puzzle was then picked up by Puzzle Crafthouse, who now produces this version. You can see the original puzzle here.
Now with a modern makeover and easier to manipulate, thanks to the handles in each piece, the basics of the Giant Puzzle remains the same.
You're given 25 pieces, 5 of each color and every one of them has a different odd number from 1 to 9, so no two pieces are the same. The puzzle comes in the state as you see it in the above picture and your task is to place the pieces in the tray so that no number or color is repeated in any row, column or any diagonal. You also have to keep in mind that in every row, column and the two major diagonals have to add up to 25, although this is achievable if you get the colors and numbers challenge right, so you don't have to think about that.
The Giant Puzzle is rated as very hard, but I actually found it to be quite easy and simple. The logic is very much similar to what you're used to in a regular Sudoku game, where you use elimination to find a correct placement for a number, in this case a piece. If you're not familiarized with the Sudoku concept, you can try separate challenges first: You can start by getting just the color pieces in the tray, so that they follow the puzzle's rules or if you prefer, start by the numbers instead. Once you have that logic learned, the full task may seem a lot easier then.
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The next two paragraphs contain spoilers on how to solve the puzzle. If you wish to try it for yourself and prefer not knowing the solution, jump to the "Closing Comments".
Ok, so when you see the puzzle for the first time, you'll notice that every row is the same color and every column has the same number, but if you look closely at the main diagonals, you can see that both of them follow the three basic rules (no repeated color, number and add to 25). Then, you just have to start placing the pieces in the order you saw them in the diagonal, but now in a row or column, which way you prefer.
Assuming you started by a column with the "Yellow 1" piece, followed by the "Red 3" and the "Blank 5" like I did, the next piece you should think about is the "Red 1". You can't place this one at the start of the second column, because you'll repeat the number 1. You can't place it in the second space, because you'll repeat the color red and the diagonal with the "Yellow 1" in the first column. You can't place it in the third space either, because it'll be in the diagonal of the "Red 3". So, by the logic of elimination, it can be placed in the fourth space. Following the same thinking, the next piece has to be the "Blank 3". Since there's six spaces in every row or column and you're now occupying the last two spaces of the second column, the logic continues at the beginning of the same column and down until completed. Repeat the same steps for the remainder of the columns and you'll have the Giant Puzzle solved. If you wish to see a picture of the solved puzzle, click this link.
Although I found the puzzle to be easier than I was expecting, it doesn't spoil the fun of solving it in any way, and if you're a collector like me, you'll most certainly want to own a high-quality copy of this classic puzzle in your collection.