Open the solver at:
http://denilsonsa.github.io/lyne-solver/lyne-solver.html

You can open it inside the Steam overlay, at an external browser, or even at your mobile phone or tablet. It just requires a modern browser and a relatively fast CPU (sometimes it takes a while to find a solution).

The complete source-code is available at: https://github.com/denilsonsa/lyne-solver

At the left of the solver there is a large text box. The puzzle must be typed in that area. The solver already comes with an example, and it gives immediate feedback when the text area is edited, which means it should be easy to figure out how it works.

Anyway, let's suppose we have the puzzle shown to the right. How do we write it in the solver? Very easy.

Each triangle becomes the letter t. Each square becomes s. Each diamond becomes d. If the shape is white at the center, then upper-case letters must be used: T, S, D.

Gray shapes become numbers. If they have two, three or four holes, use digits 2, 3 or 4.

Empty spaces become just a space in the text.

Putting all together:

After typing it, click "Solve it!". When a solution is found, it is possible to drag the "Reveal" slider to gradually reveal the solution, one line at a time. This is very useful if you are stuck and just want a little hint, without spoiling the entire solution.

This solver is as much cheating as looking at the answers on a paper crossword magazine.

LYNE is a single-player offline puzzle game. "Cheating" on it affects no one else other than the person who does it. If you are against it, don't do it. But you must not prevent other people from doing it if they want. Players should be free to do whatever they want with their own games (as long as it does not affect other players).

Also, the solver is built in a way to gradually reveal the solution, which is an automated way to give hints without having to ask other people. Sometimes a player gets stuck in one puzzle, and a small hint is enough to let the player finish the puzzle by himself/herself. An alternative is to quit the puzzle and come back later, maybe another day, with a fresh mind. Either way, it is the player choice.

The player may also have finished several puzzles in the past (maybe even in another platform), but for some reason lost the progress. If this player uses a solver to unlock the puzzles that were already solved in the past, is it cheating? I don't think so.

Bottomline: don't judge the player. Enjoy your game, and let others also enjoy it.