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# Chapter 14: Flip

You have a grid of squares, some light and some dark. Your aim is to light all the squares up at the same time. You can choose any square and flip its state from light to dark or dark to light, but when you do so, other squares around it change state as well.

Each square contains a small diagram showing which other squares change when you flip it.

## 14.1 Flip controls

This game can be played with either the keyboard or the mouse.

Left-click in a square to flip it and its associated squares, or use the cursor keys to choose a square and the space bar or Enter key to flip.

If you use the ‘Solve’ function on this game, it will mark some of the squares in red. If you click once in every square with a red mark, the game should be solved. (If you click in a square without a red mark, a red mark will appear in it to indicate that you will need to reverse that operation to reach the solution.)

(All the actions described in section 2.1 are also available.)

## 14.2 Flip parameters

These parameters are available from the ‘Custom...’ option on the ‘Type’ menu.

Width, Height
  Size of grid in squares.
Shape type
  This control determines the shape of the region which is flipped by clicking in any given square. The default setting, ‘Crosses’, causes every square to flip itself and its four immediate neighbours (or three or two if it's at an edge or corner). The other setting, ‘Random’, causes a random shape to be chosen for every square, so the game is different every time.