A worldspace 2D grid shader whose cells are selectable by mouse click.
Unity Version: 2021.3.20f1c1
For your texture import setting, set Sprite Mode - Mesh Type = Full Rect, Advanced - Wrap Mode = Repeat.
For sprite render, set Draw Mode = Tiled, then you can set Draw Mode - Size to tile your sprite.
Attach script Playground.cs to your sprite, then you can set Playground - tintRadius in editor.
Run the game, if you set Playground - tintRadius = 1, when you click the screen the first time, you will select 5 cells, centerd at where you click; the second time you click the screen, it means that you cancel the selection, and the image will return origin color.
Both shader and script are simple to read.
It can be used in puzzle or strategy games using checkerboard maps.