Hello! How long is this game to beat?
It heavily depends on how much time you need to solve all the puzzles, but, for first time players, let's say about an hour (as it's stated in the "More information" box).
Even more time may be needed if you want to discover all the Easter eggs hidden inside it.
A suggestion I like to give is to not rush things up. Every tiny particular is part of the experience.
Take your time and enjoy the story.