Right then, we all know (and take advantage of) the more amusing
bugs features in Touhou like MarisaBugged in MoF or the MAlice cannon in IN, and at least know of things like Merupo even if we've never experienced them ourselves. But tonight, I came across some interesting bugs in Subterranean Animism that I had never heard of, and while experienced players doubtlessly know about them, I can't bring myself to believe that it's common knowledge in any sense.
Therefore, in the interests of making more obscure bugs come to light, here goes.
Entry #01: When you play alongside Aya, you play alongside a GOD!
The relevant bit is at around 1:01, and picks up again at 1:40-ish.
From my understanding, (and I quote from the video description for the next example of this glitch) this bug works on all bosses that have midstage dialogue; presumably ZUN programmed the damage engine to treat them like normal enemies that could be destroyed when attacked enough. Only the ReimuC (Reimu/Aya)and MarisaB (Marisa/Patchy) bombs deal enough damage fast enough to destroy the bosses.
To wit:
Entry #02: Turning the tables on Hell's Traffic Accident
Entry #03: Wind God Girl vs Wind Good Girl
I've never encountered this bug myself, but hell yes am I going to go try them out now.
Are there any other lesser-known bugs you folks have encountered while playing Touhou? Fighting game glitches also welcome.
Note: for the purposes of this thread, demos should not really be counted, since they're riddled with bugs anyway, but I would still appreciate them being brought to light, so mention demo bugs regardless.