Brush:

You can change the size of your brush in the top left corner of the game. To change back to the brush if you are using the Fill Tool or Eraser Tool, press the right or left arrow in the top left corner of the game.

Fill Tool:

The Fill Tool is best used to fill circles, squares, or other convex shapes. It may also leave gaps if the shape is too large. It has been known to possibly slightly change the outline of the shape you fill, to prevent this, it is recommended you fill a shape with at least size 3 brush to make the outline. This tool draws many pixels on the screen and can badly lag your game if it is used many times or if more than one is being used at once.

Eraser Tool:

Use this tool to erase. The size is unchangeable.

Trash Tool:

Use this tool to delete everything on the screen. This tool can lag the game for a short period of time depending on how many pixels are drawn on the screen. This tool should remove any lag you are having from pixels on the screen (most likely caused by the fill tool).