I need a list of twitch shooters

[Fignuts]

In the vein of 1943, R-type, and raiden.

[Silent]

Einhander (PSX) was brilliant, but it's hard to find.

[Funky Fly]

Which means that there are probably some used copies readily available on Amazon or eBay... for like $100.

[G]

aero fighter 1 and 2 were awesome

[Jonster]

Anything at all in the genre?
So looking for things like Ikaruga, Psyvariar, Gunbird, Giga Wing, Mars Matrix, Trizeal, XII Stag, DonPachi, DoDonPachi, Armed Police Batrider, the entire Gradius series.

Or things a bit easier like Steel Dragon EX?

Off the top of my head that is.