The shoot'em up Touhou Project games are fan-made PC games created by a one-man game studio. Touhou Project's creator, Zun, has been free-wheeling about derivative work—something that changed earlier this year.
Touhou Project games are starting to appear in small numbers in Japanese arcades. For a special event, one Akihabara arcade put Touhou Project games in arcade cabinets, but didn't charge players play fees per se.
Another game center even has a PC mouse near the arcade buttons. These are games intended for computers and not arcade cabinets. As long as arcade operators aren't charging players, it's nice to see Touhou Project, which is inspired by arcade shooters, get a game center outing.
Touhou Project's characters Reimu Hakurei and witch Marisa Kirisame appear in spin-off fan-made manga and licensed figures.