Flipside: a paper-flipping shape puzzle
A sheet of paper is white on one side and brown on the other. Some corners have been flipped over. Flip them back in the right order until the whole sheet is white and sits on its dashed outline again.
How to play
Your first two sheets are practice: one flip each. The ? button brings them back at any time.
- Tap a corner to flip it. The corner’s triangle turns over along the line between its two neighbours. White becomes brown and brown becomes white.
- Watch where the corner lands. When a corner’s two edges are different lengths, flipping swaps them, so the corner moves and the sheet changes shape.
- Finish all white, on the dashes. The dashed outline is the finished shape. It turns to follow the sheet, so any rotation counts. A mirror image does not.
Press and hold a corner to preview the shape and colors after that flip. Let go to flip it, or slide away to cancel. Looking is free. The pegs on the dashed outline fill in as corners arrive. The number after the slash below the sheet is the fewest flips it takes to solve.
Scoring
Daily has three sheets, the same for everyone, from gentle to hard. Each one shows the fewest flips that can solve it. Match that number for three stars, finish within two extra flips for two, and any finish earns one. There are no hints in Daily. The best possible day is 9.
Unlimited is one run that gets harder with every sheet. You start with three spares, shown beside the sound button. Each flip past the shortest answer uses a spare, and a perfect sheet earns one back. At zero spares, an extra flip must finish the sheet or the run ends. The lightbulb marks the next corner of a shortest answer for one spare. Later sheets can have a pinned corner or turn off previews. Your score is how many sheets you cleared.
In Daily, Undo takes back a flip and Restart resets that sheet's count. In Unlimited, they change the sheet while keeping flips and spares already spent.
Where to start
Look at the outline before the colour. A corner that is off the dashes has to be flipped an odd number of times, so find those first. Corners next to each other overlap, which means the order matters: flipping A then B is not the same as B then A. If two flips do not touch, their order makes no difference.
When the count says three flips will do it, hold each corner and look for one that fixes a corner and whitens a large patch in a single move. That is usually the last flip of the answer, so work backwards from it.
Questions
Is every sheet solvable in the number shown?
Yes. Each sheet is made by flipping a finished one, then searched to confirm that no shorter answer exists. The number shown is the true minimum.
Can I play with a keyboard?
Yes. Focus the sheet and press 1 to 6 to flip that corner, or move between corners with the arrow keys and press Enter. Backspace undoes and R restarts.
Is there a daily puzzle?
Yes. Three sheets a day, the same for everyone, and your stars stay in this browser. Unlimited starts a fresh run whenever you like.
Where does the idea come from?
Flipside is our own take on corner-flipping polygon puzzles. The idea of flipping the corners of a two-coloured polygon comes from Flat Twist, a puzzle designed by みよしじゅんいち (Miyoshi Jun’ichi). The sheets, scoring and run mode here are ours.