Learning A New Unique
Looking at a list of popular Nikoli puzzles I came across the Nurikabe which instantly hooked me. From the puzzle above the rules are as follows:
Numbered clues indicate islands. The number in the clue showcases the amount of cells that belong to that island. These cells must not be filled in. The islands contain the numbered clue as well.
A cell in an island must not be orthogonally adjacent to the cell from another island as they would then join islands and invalidate the clues.
Between islands a continuous black line must be drawn by the player which is unbroken across the puzzle. This black line must not occupy a 2x2 block of cells.
Since I’ve only started learning how to solve this puzzle there is plenty of scope for improvement. What I’ve learned since trying to draw some few Nurikabes is that though I’ve started to develop a shorthand for the puzzle, it is important to be familiar with a variety of beginner and advanced solving solutions.
I think this point has most certainly held me back from creating workable Nurikabe puzzles, but there is another form of familiarity which must be developed: that is constantly creating and analysing these small first examples of the form. As usual I’ve started with small 5x5 grid to start learning how to design these puzzles.
I’ve found two initial approaches to designing Nurikabe puzzles that of course need to be joined together but that are still separate in my neophyte form. The first is to design by establishing a route that moves through the grid. Figuring out the spacing and direction of the black line as it moves through the grid. The second approach is defining the island clues: where are they placed and what value do they have.
If these approaches are made separately then one approach will utterly determine the other. What I want to work towards in the following weeks is combining these two approaches so that I understand what certain clues and island spaces will do for the player path and vice versa. There’s an interesting parallel, however, with labyrinth design and the difficulty of keeping both the path and wall design in mind at the same time.
I was having trouble making any Nurikabe puzzle with a unique solution. But the most recent experimentation bore fruit at last. I took a smaller 3x3 corner of the grid and experimented with that space. Using a number 2 clue in the corner it showed exactly what i could do with the space. From that clue I worked on the black line and how that should withing the 3x3 and beyond.
What we see here is a later iteration on the puzzle. one way to ensure some form of uniqueness when starting to design these types of puzzles is to add lots of constraints. This makes the puzzle easier for the player but it teaches the designer how to make a unique one when starting out. The only clue which broke that uniqueness was the 3 in the top left. Changing that to a 4 made the whole puzzle click.
Going forward I’ll continue with adding lots of island clues, which makes the puzzle easier but helps me get used to the format. From there I can learn how to pull back from that constraint heavy type of nurikabe. This is similar to how I engaged with nonogram puzzles when learning how to draw them.
