Connection

You match identical tiles, but only if a path can be drawn between them - usually with a limited number of turns and without crossing other tiles. Seeing the pair is easy; finding a legal route is the puzzle.

Because the path between them is blocked or needs too many turns. Most versions allow two turns at most, so tiles on opposite sides of a full board often cannot be joined until something between them clears.

Fruit Connect 3. It uses the standard rules with a clear board, so you can learn how the path restriction behaves before trying versions that add other systems.

Mahjong Crimes - Puzzle Story runs a case alongside the boards, so clearing one advances a narrative rather than simply unlocking the next layout.

Yes, all of them run free in your browser with nothing to install and no account needed before you start, and none of them limit how many boards you can attempt.