Doodle chain is a logical game with random generation of levels.
The goal of the game is to fill all the space at the level with a chain. To create a chain click on the part of the screen relative to the last link of the chain.
Random generation provides an opportunity to go through an infinite number of different levels (note that generation may occasionally encounter similar levels). If the current level is too complicated for you or for some other reason you do not want to go through it you can always generate another using the button on the screen.