Just looking at the game, I'm guessing you need to already have some knowledge of Cantonese writing?
Not necessarily, the way I see it you can just jump in and start learning and practicing. Now is there a correct way to write the strokes, technically yes there is (which fun fact, Chinese writing is designed for right handed people. My wife is a native speaker from Hong Kong but she's a lefty, so she adjusted all stroke writing from the left handed perspective ;D), however, I would say writing the strokes properly when the goal is to learn how to read/speak/hear Cantonese is the main goal is alright. Will you have to unlearn bad habits or re-train yourself to write the strokes properly? Yes, this may be a possibility. Of course you could just research how to write the strokes from the beginning.
The Cantonese Scrolls is a project to document and teach the language, and record the characters for its direct written form. It doesn't contain every single aspect or tool for language learning, but the core material to preserve the language, let's say 250 years later when someone unearths it. This is also why I called it a scroll, since I view it as a sort of digital ancient document written on parchment paper haha.