What it is

Corner Flip is a sibling of Tile Flip (#16) and the original Lights Out, but with a single rule changed: clicking a tile toggles only its four diagonal-corner neighbours. The tile you clicked stays exactly as it was, and the four tiles sharing an edge with it are untouched. Only the four diagonals flip. Your job is the same — turn a partially-lit board fully dark — but the structure of the puzzle is genuinely different.

How to play

Click or tap a tile. Its four diagonal corners flip (lit↔dark). The tile itself does not change.
Goal: every tile dark.
Levels grow longer the further you get — more scrambled starting states.
Solvability is guaranteed — boards are generated by applying random clicks to a solved board.
No clock. Think it through.

The trick

Here's why Corner Flip is mathematically distinct from Tile Flip: the diagonal move splits the board into two independent sub-puzzles. A diagonal step always lands you on a tile of the same "colour" if you imagine the grid as a chessboard — so the 13 "white" tiles and the 12 "black" tiles never interact. You can (and should) solve them as two separate problems. Recognising this halves the apparent difficulty: instead of one 25-tile puzzle, you have a 13-tile puzzle and a 12-tile puzzle, each smaller and more tractable. Players who don't see the chessboard split tend to thrash; players who do solve calmly.

What this scored well on

It teaches a real idea. The chessboard decomposition is a genuine piece of mathematical insight, and the game is structured so a curious player will discover it on their own. That "oh!" moment is the whole reason this game exists.
It's a true variant, not a reskin. We were careful that Corner Flip and Tile Flip play differently enough to both earn a slot. The diagonal rule isn't cosmetic — it changes the solving strategy completely.
Generative solvability. Like Tile Flip, every board is reachable because we build it by scrambling a solved board.

What it gets wrong

Corner Flip has the same plateau problem as Tile Flip: once you've internalised the chessboard split, the levels stop feeling distinct. It's also less immediately intuitive than Tile Flip — new players sometimes don't notice that the tile they clicked didn't change, and get confused. We added a subtle hover preview in an earlier build and removed it; it gave away the diagonal pattern too obviously and killed the discovery. The trade-off is that the first few levels can feel opaque.

Who it's for

Corner Flip is for players who enjoyed Tile Flip and want the same genre with a real mechanical twist, and for anyone who likes puzzles that secretly teach a mathematical structure. If you've already had the chessboard insight, it becomes a calm, methodical solve; if you haven't, the moment you get it is worth the price of admission.

Where we'd point you next

Play Tile Flip (#16) back-to-back with this one — feeling the difference between the two rule sets is the best way to appreciate either. If you liked the deduction, try Code Crack (#11).

Released · 13 May 2026 · Editor's score 3.7 / 5 · Reviewed by Bill