Tiles are the background artwork of a game. They are rectangular areas of image data, usually non trasparent and with a fixed size like 32x32 or 64x64; this values may vary.


Tiles are put into an image file and for the level creation, the game programmer makes a program called the Level Editor. With this tool the programmer allows level designers to pick the tiles for every part of the level easily, usually using the mouse and the keyboard. The other option is to create the level by code, as shown here:

LEVEL levels[50] = {21,30,2,5,10,50,32,41,22,22,23,45};

Which is very tedious and difficult sometimes. Professional game programmers always use a level editor. There are level editors released to the public, like those of Duke Nukem 3D, Blood, Quake, to name a few.