The player takes the role of a young boy, Michael Kennedy, who receives a mysterious letter from his missing father and begins a quest to find him.

He finds a letter from his father Taylor, which states that he has been hired for an "off the books" construction job in a valley down the road from their mountain home, and that he could be dead by the time Michael reads it.

The game features four different areas that are explored in sequence, consisting of Michael's house, a construction site, and the exterior and interior of a medical testing facility.

[1] Eli Brewer was inspired to make The Letter after listening to soundtracks of horror games including Eternal Darkness: Sanity's Requiem, ZombiU, Call of Duty: Zombies, and Resident Evil.

[14] Nintendo Life's Dave Letcavage, awarding the game one out of ten stars, named it a "half-formed thought scribbled, almost illegibly, across a post-it note".

[13] In a review for Hardcore Gamer, Nikola Suprak gave The Letter a one out of five, concluding that the game "needs to die an unloved death on the Nintendo eShop purchased by absolutely no one".

[2] Daan Koopman, writing for Nintendo World Report, said that it "shows that honest intentions will not always get you a good game", and he scored it a two out of ten.