Sacheonseong

My record

Tap two tiles with the same picture one after the other to remove them.
The two tiles must be linkable by a line with at most two turns (three straight segments or fewer), passing only through empty spaces.
The ring just outside the board also counts as empty, so edge tiles can be linked around the outside.
Clear every tile to win! If no pairs are left you can shuffle; when the shuffles run out, the game is lost.
Each picture appears on 4 tiles. Which two you remove first can decide whether the board gets stuck.
Every new board is generated so that at least one full solution exists.

Hint: flashes a pair you can remove right now (5 on Easy, 3 on Normal and Hard).
Shuffle: reshuffles the remaining tiles so they can still be solved (3 on Easy, 2 on Normal, 1 on Hard).
Undo: brings back the last pair you removed. You cannot undo past a shuffle.
On narrow screens such as phones, the board is turned upright so the tiles stay large.