Actual (short) explanation of what Len'en is for the people wondering

"The Len'en Project (連縁Project / 鏈縁Project lit. Connecting Chain) is a Japanese doujin game series that specialises in shoot 'em ups by Trick Nostalgie, whose sole member is game developer JynX." (From Len'en wiki)

It takes a lot of inspiration from Touhou Project but the lore and characters are notably different

JynX also said it's a "homage" to ZUN and Touhou, since they're a huge fan of it

https://cdn.comic.studio/images/lenenproject/backgrounds/3a7af223e074a2261354bbe320d501f3.png?filename=image_46.png
(Added image to make it more interesting)