Monument valley is a mobile game developed by Ustwo. The intended audience is really anyone old enough to understand the visual complexity of the puzzles (not young children). The formal elements add a lot to the play experience. It is a single-player game where the goal is to complete puzzles to return artifacts to these different monuments in that you play through. As far as I can see, there is no way to “lose” the game, making it a non zero-sum game. The boundaries of the game are less obvious than they may originally appear because the game itself changes the boundaries as you play along. Within an individual level, you may only see a very small portion of it at a time with no clues as to how large it actually is. I think that this really adds to the play experience for making the puzzles seem more challenging due to lack of information.
There are only a few mechanics in this game, but they add quite a lot to the game experience, specifically making the puzzles much more difficult. First, you can move by just tapping where on the path you would like to go, and you will move there as long as it is possible to go there. This in and of itself might make the puzzles seem pretty easy since all your character actually does is move; however, players need to also keep track of the environment around them. For example, some pieces of the architecture can actually slide, either moving up and down or side to side. With these, not only does it move the piece you are actually sliding, but there’s also the possibility that this will then move other pieces, so players need to not only keep track of how the one piece moves but also how the other pieces move as a result. Additionally, there are two types of buttons that actually combine the mechanics of character movement with the necessary environmental awareness. This makes the player focus a lot more on how they need to move in the context of the environment since interactions with the environment need to be done in a certain order. These limited mechanics really create a great puzzle solving experience. It really frees the user to think more deeply about how to solve the puzzle rather than how the game works, which I think is really beneficial for gameplay overall.
I would also say that to some degree these limited mechanics actually take away from the actual story to some degree. At least with how far I got into the game, the story scenes (when talking to the ghost-like character) have their own “rooms” and don’t actually require any of the architecture interactions and very limited movement, so they feel very disconnected from the game itself, whereas if these character interactions happened in the normal game levels, or where you had to try harder to actually talk to the ghost once in the room with them, I believe that it would feel more integrated.