Solution of Lights Out (Classic):

Number the rows 1-5, the columns A-E.

1. For each light on row 1, press the button beneath it on row 2 to turn the light off. This way row 1 is completely unlit.
2. Repeat step a for rows 2-4, so that now you only have lights on row 5. This is usually called 'chasing the lights'.
3. If the light at A5 is on, press D1 and E1.
   If the light at B5 is on, press B1 and E1.
   If the light at C5 is on, press D1.
4. Repeat steps a-b, chasing the lights down and it will be magically solved.

This method will not solve the puzzle in the shortest possible way, but it is very simple.

Solution to the Mini Lights Out:

This is an easy puzzle once you know the following two facts:
1. To change an individual light, press it and its four neighbours.
2. To know whether you need to press a button or not, check its own light and the neighbouring lights. If an odd number of these 5 lights are switched on, then the button needs to be pressed, otherwise it does not.

The following solution then suggests itself:
a. Use fact 2 above on all the buttons in the middle two rows.
b. For each light that is on in row 2, press the button above it in row 1.
c. For each light that is on in row 3, press the button below it in row 4.

Lit Only games:

The lit-only game is solved in nearly the same manner as the normal game. Simply figure out whether any of the lit buttons need to be pressed, and then press them. If any unlit button needs to be pressed, you will need to delay pressing it until other button presses have lit it. Occasionally all buttons that remain in the solution are unlit, so then some lit button has to be pressed first to allow you to move on. Later that same button will have to be pressed again, since it wouldn't have been part of the solution if you hadn't been forced to press it the first time. This situation can usually be avoided.

I have proved that any position that is solvable in a normal variation of the lights-out is also solvable as the lit-only game. The proof of this is given on the Lights Out Mathematics page.

Solution to Lights Out 2000:

1. For each light on row 1, press the button beneath it on row 2 once or twice to turn the light off. This way row 1 is completely unlit.
2. Repeat step a for rows 2-4, so that now you only have lights on row 5. This is usually called 'chasing the lights'.
3. If the light at A5 is red then press B1 twice, if it is green press it once.
   If the light at B5 is red then press A1 and B1 twice, if it is green press them once.
4. Repeat steps a-b, chasing the lights down and it will be magically solved.

To get a minimal solution, the same method can be used as for the classic version, except that there are now 26 quiet positions to check.

The built-in puzzle problems can be solved using the above method, or you can simply look up the solution on this page, which also includes the solutions to the built-in puzzles of the classic game.

Solution to the Lights Out Cube:

1. Number the buttons/lights as shown above (which is different to the numbering in the manual).
2. First you must simplify the position by chasing the lights:
   If 5 is lit, then press it to switch it off.
   If 1, 2 or 3 are lit, then press the buttons below them, i.e. 21, 20, or 19, to switch them off.
   If 7, 8 or 9 are lit, then press the buttons below them, i.e. 13, 14, or 15, to switch them off.
   If 4 or 6 are lit, then press the buttons below them, i.e. 11 or 17, to switch them off.
   If any of 10-21 are lit, then press the buttons below them, i.e. 22-33 to switch them off.
   If any of 22-33 are lit, then press the buttons below them, i.e. 34-45 to switch them off.
   If 35 or 41 are lit, then press the buttons below them, i.e. 49 or 51, to switch them off.
   If 37, 38, or 39 are lit, then press the bottoms below them, i.e. 46, 47, or 48, to switch them off.
   If 43, 44, or 45 are lit, then press the bottoms below them, i.e. 54, 53, or 52, to switch them off.
   If 50 is lit, then press it to switch it off.
3. There are now only lights on in the bottom face or at 34, 36, 40, 42.
   If 40 is lit, then press the buttons 3 and 4.
   If 36 is lit, then press the buttons 4 and 16.
   If 46 is lit, then press the buttons 16 and 10.
   If 34 is lit, then press the buttons 10 and 1.
   If 47 is lit, then press the buttons 4.
   If 49 is lit, then press the buttons 2, 12 and 16.
4. Repeat step b, chasing the lights down and it will be magically solved.

Solution for Lights Out Deluxe (move type +):

1. For each light on row 1, press the button beneath it on row 2 to turn the light off. This way row 1 is completely unlit.
2. Repeat step a for rows 2-5, so that now you only have lights on row 6.
3. If the light at A6 is on, press A1 and C1.
   If the light at B6 is on, press D1.
   If the light at C6 is on, press A1 and E1.
   If the light at D6 is on, press B1 and F1.
   If the light at E6 is on, press C1.
   If the light at F6 is on, press D1 and F1.
4. Repeat steps a-b, chasing the lights down and it will be magically solved.

As there are no quiet patterns on this board size, this solution will always use the minimal number of moves if you cancel out duplicate moves from the two chases (or restart the game once you know which buttons to press on the top row).

Solution for Lights Out Deluxe (move type ×):

1. Press a combination of buttons on row 2 such that the lights on row 1 are switched off. This seems tricky, but is quite easy once you know how. First switch off lights A1, C1, E1 from left to right as follows:
   1. If A1 is on then press B2.
   2. If C1 is on then press D2.
   3. If E1 is on then press F2.
   Next switch off lights A2, A4, A6 from right to left as follows:
   1. If F1 is on then press E2.
   2. If D1 is on then press C2.
   3. If B1 is on then press A2.
   Now row 1 is completely unlit.
2. Repeat step a for rows 2-5, so that now you only have lights on row 6.
3. If the light at A6 is on, press F1.
   If the light at B6 is on, press E1.
   If the light at C6 is on, press D1.
   If the light at D6 is on, press C1.
   If the light at E6 is on, press B1.
   If the light at F6 is on, press A1.
   Note how the button pattern to press on the top row is the mirror image of the light pattern on the bottom row.
4. Repeat steps a-b, chasing the lights down and it will be magically solved.

For this move type there are again no quiet patterns, so this solution will always use the minimal number of moves if you cancel out duplicate moves from the two chases (or restart the game once you know which buttons to press on the top row).

An interesting thing about the diagonal cross shape is that if you were to colour the game square like a chess board, then each move only affects squares of one colour. This shows that this puzzle therefore actually consists of two independent puzzles that are solved simultaneously. In the regular or lit-only game, you can actually solve one of these sets completely before tackling the other.

Solution for Gamze Lights Out, × move:

First we shall solve the 3×3 subproblem.

1. Imagine the 3×3 subgrid is numbered 1 to 9 in the obvious manner.
2. To see whether edge button 8 has to be pressed or not, look at lights 1, 2, 3, and 5, i.e. the three lights on the opposite side of the square together with the centre one. If one or three of those four lights are on, then press button 8. If an even number of them is on, do not press it.
3. Repeat step b with the other three edge buttons.
4. The five remaining buttons, the corners and the centre, are now simple to solve. Of those five buttons, press the lit ones and do not press the unlit ones. The 3×3 grid should now be all off.

Now we solve the 4×4 subproblem.

1. Orient the puzzle so that the top row of the 4×4 grid has as few lights on as possible.
2. If pressing a top corner would switch off three lights, then do so.
3. Switch off the top row completely by pressing the button directly below any lit top row square.
4. Switch off the second row the same way but pressing the buttons on the third row.
5. Switch off the third row the same way but pressing the buttons on the bottom row. When you have finished, the bottom row will automatically be solved too.

The 4×4 part of the solution will not necessarily be optimal, but will take at most 4 moves too many. This is well within the margin that the game allows.

Solution for the Original Merlin Magic Square Game:

The squares are numbered 1-9 in the normal way.

1. For edge button 8, look at the lights 4, 5, 6, 7, 8, and 9 which form a 2×3 rectangle along that edge of the board. If an even number of lights in this rectangle are on, then press button 8. Do the same for each of the other edge buttons, using the rectangle along those sides instead.
2. Press any unlit corner buttons.
3. If the centre light 5 is on, then press it to switch it off.

Solution for the reissued Merlin Magic Square Game:

The squares are numbered 1-9 in the normal way.

1. For edge button 8, look at the lights 1, 2, 3, and 5 which form a T on the opposite edge of the board. If an even number of these lights are on, then press button 8. Do the same for each of the other edge buttons, using the T-shape along those opposite sides instead.
2. Press any unlit corner buttons.
3. If the centre light 5 is on, then press it to switch it off.

Solution for the XL-25 Knight's game:

1. Try to solve as many of the lights as possible by a few button presses.
2. Find a light that you want to change.
3. Find a pattern in the top row in the table below that matches that light. You may need to rotate or reflect the pattern to get a match.
4. Press the buttons in the corresponding pattern in the bottom row of the table. This changes the light.
5. Repeat b-d until all the lights are correct.

These patterns can also be used another way since the game is a symmetric one (i.e. buttons mutually affect each other). This gives a method to solve the game in the minimum number of moves.

1. Choose any button for which you want to determine if it needs to be pressed or not.
2. Find a pattern in the top row that matches that button. You may need to rotate or reflect the pattern to get a match.
3. Look at the corresponding pattern of lights given in the bottom row. If an odd number of the marked lights are incorrect then the button needs to be pressed, otherwise it does not.
4. Repeat a-c for all the buttons in turn.