The genre is strongly associated with Japanese developers, but some Western ones have materialized here and there.
Here are the ones I know off the top of my head:
Katakis (1987 C64, 1988 Amiga) / Denaris (1989 C64/Amiga)
Menace (1988 Amiga/ST/C64)
Armalyte (1988 Amiga/C64)
Blood Money (1989 Amiga/ST/C64/DOS)
SWIV (1991 Amiga/ST/C64)
Agony (1992 Amiga)
Apidya (1992 Amiga)
Firepower 2000 / Super SWIV (1992 SNES) / Mega SWIV (1994 Mega Drive)
Raptor: Call of the Shadows (1994 DOS)
Kolibri (1995 32x)
DemonStar (1998 Windows)
What am I missing? This is mainly a list thread, but also a discussion. Do you think Western shmups (the few that did get made) were really worse than Japanese ones? Is there anything in particular, sylistically or otherwise, that makes Western shmups distinct? What factors made Western shmups less popular and less numerous?