I'm only about half into Touhou apart from the camera ones, which are genius (and, yes, only tenuously shooters - I don't care). As far as pretend arcade games go, Zen-Ichi (train stage! why is there always a train stage?) is fabulous. Kind of old and import only, so you might end up needing to resort to piracy to find it. I also quite like Acceleration of Suguri, a fighter/shooter hybrid like Senko no Ronde or Virtual On in 2d. Looks like utter arse, but that doesn't hurt it too much. As in Suguri, the main gimmick is a dash that goes (sort of) safely through energy projectiles but not solid ones. You can get that on Gamersgate or PSN in English, so at least it's easy to find. I assume there's a demo.
Nice. The Shanghai Alice shooters are a league of their own. I actually forgot they were doujin. I've already got most of them . 16bit are almost unplayable for me these days.