I recently worked on a game for the jame gam, called Diaper Baby.

So now I am making another more meaningful game, you scribble the canvas to reveal messages and then once you have revealed it you can move on.

This is the MVP, so you will probably find workarounds in the game.

How the game works:
I used React-konva (a library that lets you set a canvas). I set two layers, one was of text and one was of the coat layer. The coat layer stays above the text and you have the eraser tool set up, and when you erase the coat layer it reveals the message.

Once the message is partially or fully revealed, the arrow is shown.