[thaumasiotes]

The secret rules appear to be:

- You have to use all the tiles.

- The ball must visit every part of every tile.

- The finished layout must look elegant.

Just assume that there is no goal other than closing all the paths. A tile that connects to empty space means you're wrong. A tile that connects to another tile means you're right. Any and all other "rules" will be changed as necessary to ensure that, if a solution is pretty, it's also correct.

[infthi]

Counterexample (working solution): https://imgur.com/a/VxDJc6M, level 9

* all the tiles are used: yes

* every part of every tile visited: no. bottom right tile is not visited at all; the dangling path of the three-way tile is not visited

* elegant: no. Dangling paths.

[pdpi]

That's not a puzzle, though. It's just testing whether we agree on what "elegant" means.