Brothers: A tale of two sons.
The game has a pretty unique mechanic. It makes you control two characters at the same time. It's not a coop game, with optional solo. It's strictly a single player game, where you use one controller to move two characters, the titular two sons, one on each control stick. Throughout the game you use movement and interactions with the environment to solve simple puzzles to remove obstacles in your way and travel to your destination. Usually, by having you do different things with each character simultaneously. After a while, it becomes second nature to control both brothers in a synchronous and flowing manner when you get used to the challenge of moving and paying attention to two different things at the same time.
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Near the end of game though, one of the brothers dies. Now, you are left with two control sets, but only one character. Puzzles similar to ones that you already solved, now you have to figure out how to solve them, on your own. This on its own is gutwrenching as you developed a familiarity and affection to both characters and their dynamic, as they grow from mutually annoyed siblings, to a well coordinated team of brothers who care and protect each other.
But through the game, you're also taught that the younger brother can't swim, he doesn't know how to. So whenever you had to cross a body of water, the elder brother had to carry the younger brother on his back. He is deadly afraid of being in the water since their mother apparently drowned herself and he saw her die.
At the climax of the game, alone in the middle of the ocean, you have to swim to shore. The emotional kicker is as you discover that using the dead brother's stick on your controller, which you haven't touched in at least half an hour since the other brother died because it doesn't do anything anymore, calls however upon the memory of the older brother when you swim. You have to use both controller's sticks to swim effectively and survive, and you can hear him cheering and supporting the younger brother to find his strength and swim on his own, back home, to carry on and save their father's life.
It's such an empowering and emotional moment.
The ending of that game still makes me tear up after all this years as it makes me think of my own family. Even writing this comment I'm getting emotional. And it does it all without a single line of dialogue, text or voice acting. All by animation and vocalizations along with game mechanics. It's one of the most effective uses of gameplay I have ever seen in a video game and forever has made me think of this as one of my favorite games of all time.
Other video games, and things people call emotional are usually about story elements, plot lines, events on a character's arc. Things that have books upon books of analysis and history. Not that they're any less valuable or deserving of praise, but using gameplay this effectively to convey emotion is, however, kind of unique and rather harder to pull off effectively.