Perhaps a set of starting lights would be more appropriate for a preview of a first round than a chequered flag, but somehow they feel much less iconic…
The first round of the World Puzzle Federation‘s Puzzle Grand Prix competition takes place this weekend, starting at 11am UK time on Friday and running through to 11pm on Monday night. During that time, you can choose the 1½ hour window of your choice in which to attempt the 24 puzzles in the first round’s booklet. Register for the contest, log in, download the encrypted .pdf file containing the puzzles, use the web page to confirm you want to start your clock and then you will be provided with the password to decrypt the puzzle file. (You may want to print the puzzles out, but it’s not obligatory.) You can then submit answers to as many puzzles as you have solved as many times as you like before the 90 minutes expire.
The instruction booklet for the first round has been made available; the first round contains three examples of each of eight styles of puzzle. The puzzles attract different numbers of points according to their perceived difficulty. This year’s contest seems to be favouring relatively many, relatively light puzzles over last year’s assortment of relatively few, relatively hard ones, making the contest more accessible than ever before. There are three examples of each of:
- Minesweeper, well-known as the puzzle in earlier versions of Windows (or online), except that many of the numbers of adjacent mines are given in advance without having to click around;
- Nurikabe, a path-colouring puzzle where you deliberately aim to leave certain patterns of cells uncovered. The best way to get started is the Nikoli tutorial; Nikoli have sample puzzles to solve, as do other sites;
- Tents, in which you are presented with a grid of trees, which must be filled with tents according to certain rules. Brainbashers has a tutorial and sample puzzles, as does Maths Is Fun;
- non-specific word grid puzzles where letters must be placed into cells in order to spell out given words, in the style of an unfinished crossword without any black spaces. This sort of puzzle has appeared before on US Puzzle Championship tests;
- Different Neighbors [sic] puzzles whose entire description is Put a digit from 1-4 into each cell so that adjacent cells never contain the same digit, not even diagonally. Some cells have already been filled for you, as exemplified here and briefly discussed at LMI;
- Fillomino, a puzzle involving filling a part-filled grid with digits so that it can be split into regions of identical numbers, with size equal to the number in question. Brainbashers again has a tutorial and sample puzzles, as does Math In English;
- Slitherlink Out-Liars is a variant on the well-known Slitherlink (Fences, Rundweg, Loopy, etc.) loop-forming puzzle in which all numbers outside the loop are liars, and all numbers inside the loop tell the truth and
- Shikaku Liars is a variant on the well-known Shikaku (Rectangles, etc.) puzzle in which a grid must be split into rectangles with given areas.
At least one example in each of the eight types has been set with a deliberately low tariff, so you may well be able to get to grips with at least one puzzle of each type. If you ever want to try one of these middle-distance puzzle contests, and participate in a global puzzle contest with likely hundreds of competitors from dozens of countries, this will be a genuinely accessible example of the form, and one where you can get familiar with at least most of the puzzle styles in advance. Simon Tatham’s Portable Puzzle Collection is a good way to practice, available at no cost on a wide variety of operating systems.