Corral, also known as 'Bag' or 'Cave', is a Nikoli puzzle in which the aim of the game is to draw a single, closed loop along the grid lines, while following several rules. The game could be played on any grid, but the bigger the grid the harder the puzzle usually becomes. Part of the difficulty does lie within the placement of the numbers however.
The rules are simple:
- Draw a single, closed loop along the grid lines.
- The loop must enclose every circle on the grid.
- The grid cannot intersect itself.
- Each number shows how many cells can be seen from the number's cell in a horizontal and vertical direction. The number's own square is counted.
The standard puzzle is relatively easy. The biggest challenge lies in figuring out how to piece together the enclosed areas. If the last rule is confusing, perhaps the following will help clear things up:
Consider the line you draw to be an actual wall. The numbers represent how many rooms (cells) in total you can see before looking at a wall in each horizontal and vertical direction. So in the example below the number 2 at the top shows that from this number only 2 rooms can be seen in total, including the room the number 2 is in. The only option you have is to extend the room downward, as both left and right would cause you to break the rules further down the line.
Each puzzle is supposed to have a single solution. This isn't hugely important in a regular puzzle, but it can be of importance when you convert it to an RPG setting. If there's two or more solutions it means there are 2 or more paths and thus 2 or more things to keep track of.
The Corral puzzle is a great one for RPG settings, as these puzzles can be used to show all sorts of secret paths.
Consider the example below:
My character is faced with a single platform in an otherwise dark room. There's a portal at the opposite side and all my character's been given is a handful of numbers, which are said to contain the safe path to that portal.
As long as my character sticks to the path she'll make it to the portal, but if at any point she moves too far she'll drop into an abyss and face the consequences.
This puzzle can be adapted in all sorts of similar ways. The safe path through a mine field, the right way through a maze, the instructions of a person who doesn't speak your language, and so on. You could even include treasures in the little side rooms, like the one marked by number 5 in the examples.