The sprite sheet was automatically sliced up into hundreds of 128 x 128-pixel sprite squares. We created the prefab objects from some of these sprites so that the copies can be created at runtime when needed.

The text file called level1.txt contains the lines of text characters. Each non-space character represents where a sprite prefab should be instantiated (column = x; row = y). These characters have been chosen so that the text file is human-readable. As shown in the following screenshot, when displayed in a text editor with a fixed-width (typewriter) font, the text file gives us a good idea of how the actual sprite-based graphical 2D map will look:

In the LoadMapFromTextfile script class, a C# dictionary variable named dictionary is declared and initialized in the Start() method to associate the specific prefab GameObjects with some particular...