Grids is a big library, and it may not be obvious how to start, or where to look when you know what you want to do. Here are some basic pointers.

Grids can be built in the editor, using one of the grid builders, or can be directly built in code.

You will usually want to use the first method – it’s much simpler, and the visual feedback in the editor makes it easy to see what is going on. Building grids in code is useful when you want more control and want to use advanced techniques. Grids built in code is also useful for certain types of algorithms, where the “cells” are not Unity objects.

Start by selecting the appropriate grid builder, and build a grid using the appropriate example prefab. Once you have your grid setup in the editor, the next step is to give add the logic you will need for your game. There are usually two parts:

Cells are usually quite lightweight. The bulk of the logic will be in your GridBehaviour.

The GridBevahiour gives you access to the two main objects you will work with: the grid and the map:

You can usually implement the logic in your GridBehaviour in four steps:

For example, the game Lights Out may be implemented as follows:

Similarly, a match-3 game with falling blocks may be implemented as follows:

Of course, game development is not usually as neat as this. In general, you may implement the four steps very crudely, and then move on to refine them.

You can find more detailed information in various articles: