Make All Happy

Make All Happy is a toggle puzzle with a cheerful face on it. The board is a grid of blocks, some happy and some not, and you change them by tapping. The catch is that a tap never affects one block alone: it switches the block you touched along with its horizontal and vertical neighbours. The level is solved when every block on the board is happy at once.

That rule makes the game more logical than it first looks. Fixing one unhappy block will usually upset the ones next to it, so random tapping tends to go in circles. The useful question is which set of taps, taken together, changes exactly the blocks that need changing.

Two observations help. If each block simply flips between two states, tapping the same block twice puts everything back as it was, so no block ever needs more than one tap. And the order in which you tap does not change the final board, only which blocks you chose.

1. Look at which blocks are not yet happy.
2. Tap a block to switch it and its neighbours.
3. Watch how each tap changes the cross of blocks around it.
4. Keep toggling until the whole board is happy.

Work row by row. Fix the top row by tapping the blocks directly beneath any unhappy ones, then repeat downwards; the last row shows whether your first-row taps need changing.