In this review I'll give a plot synopsis, so it will contain slight spoilers.
"The Gensokyo of Humans" is a story about Hieda no Akyuu, a character who hasn't featured in the games yet but appears in Memorizable Gensokyo and Forbidden Scrollery.
Akyuu has the ability of perfect memory. Her job is to write the Gensokyou Chronicle, and she has done so throughout multiple lifetimes, reincarnating for the ninth time now. She was born as the head of a great household, holding the important position as chronicler and suffering from a shortened lifespan due to her ability and reincarnation.
In this story, her health and mental state begins to rapidly deteriorate. She keeps seeing her cat, which died a year ago, and begins forgetting things she should be able to remember perfectly. While she slowly falls into despair and begins to doubt the purpose of her life as a chronicler, Reimu, Marisa and her best friend Motoori Kosuzu are frantically looking for a solution to the illness that has befallen her, refusing to admit the possibility that her life might be coming to an end naturally.
It's a very sombre story. The art is drawn in dark tones, the characters look slightly older and less cute than in many other works, and the themes are also darker than your usual Touhou storyline, centring mostly around loss and the meaning of life and death.
It might not be canon, but I highly recommend giving this a read.
