The gameplay of this game could be defined as a pure point-and-click.
There are no dialogues except these that the protagonist do with himself, this partly because of the nature of the game. He is alone on an island and he knows virtually nothing.
About the programming stuf of the game logic I just thought about putting a contextual comment about the situation and progress level in history at the end of each movement of the protagonist. These comments are sometimes generic and sometimes targeted to steer you in the right direction the game.
Tips are sometimes my quotes or from famous people. Tips are somehow related to the situation and the theme of the game.
Progress in the game is defined by some variables related to the resolution of the puzzles.
Even the ability to move between the scenes is updated from time to time, restricted or enabled as a function of the resolution of the puzzles. For example, once you find the way out of "endless beaches" of the first level of the first chapter, you can no longer go back.
Technically speaking, saving the game variables is done at the level of JavaScript with the functions: