Before Minecraft, Touhou was the only indie game I'd ever seen toys for in a high street shop. The long-running series of bullet hell shooters are dōjin soft created by a developer known as ZUN, whose prolificacy has led to 23 games plus a world of books, comics, music, figurines, pillows, unofficial fan games and more.
Of course, that aforementioned shop was in Japan, since the Touhou games have never been officially released in English. Playism are now planning on changing that with Touhou 14: Double Dealing Character [wiki page].
Here's 30 minutes of YouTube user Jaimers91 playing Double Dealing Character in 'Lunatic' mode:
One half of the Touhou games' success is due to their bullet hell mechanics, which challenge players to dart between patterns of projectiles that blot out the screen and kill the player instantly if touched. The other half is the games' cast of anime witches, who the player controls, fights, and is friends with depending on the particular game. That means that an English translation might be significant - these are games that can be played even when you don't understand the language, but there's arguably part of the experience that you're missing.
That said, I doubt you're about to find Touhou books in a Waterstones near you. Bullet hell has a long legacy of success in the east and not much exposure at all in the west, and if you were previously keen to play the series, there were robust and swiftly made fan translations already available.
Touhou creator ZUN now works under the company name Team Shanghai Alice, which is coincidentally also a three-word story explaining how we got Alice to work here.