Flip
Why does clicking twice undo a move in Flip?
Each move toggles a fixed group of cells. Toggling the same group twice restores every affected cell. Read the small diagram in the selected cell: different puzzle settings can use different move shapes.
Worked example
If a move switches three lights, repeating it switches those same three back. Judge the whole group, not just the clicked cell.
What to check on your board
Apply the rule above to your current board, then verify the remaining puzzle constraints. The example explains a local deduction; it is not a solution to every randomly generated board.
Checking your next move
Inspect the move diagram before clicking, and mark every cell that will change. If a trial move makes the board worse, repeating that exact move restores the previous state. Compare whole affected groups rather than selecting moves only because the clicked square has the wrong colour.
Using this reference
For Flip, read the rule and the worked example together before opening the game. Separate what the rule explicitly requires from what only seems likely on the current board. A useful next move is one you can explain from the visible constraints, not merely a pattern that looks familiar.
If you get stuck, isolate a smaller part of the position and list what is still possible there. After a move, check the affected rows, regions or connections again. The reference explains the documented rules; progress, controls and save behavior belong to the linked game.
Read the developer’s manual ↗ · Open the developer’s browser version ↗
Manual inspected: · Simon Tatham & contributors · MIT