Essential SHMUPS

[FatCobra]

Raiden I & II are the quintiessnal vertical shmups, IMHO.

[MadSteelDarkness]

Excellent topic, CMoon...

But a damn hard question. llabniP's list is excellent, but I would propose a few additions/subtractions:

Verts:
Galaga
Xevious
Twin Cobra
Raiden
Batsugun
Layer Section
Strikers 1945
Battle Garegga
Dodonpachi
Ikaruga

Verts (with a horizontal aspect ratio):
Zanac
Soldier Blade
Radiant Silvergun
Mars Matrix

Horis:
Scramble
Gradius
R-Type
Darius
Thunderforce III
Border Down
Gradius V

Of course, this list eliminates many of my favorites. But I feel that each one was a significant step forward from previous games, or was at least unique enough, to merit "essential" status.

It would be like someone saying they wanted to get into Jazz and replying 'just buy everything by Coltrane'...hmmm, we're looking for something more diverse.

So buy everything by Miles Davis.

Well, you could, but then you'd be missing out on great (and very essential) artists like Jelly Roll Morton, Duke Ellington, Charlie Parker, Clifford Brown, Charles Mingus, Thelonius Monk, Sonny Rollins, Art Blakey, Eric Dolphy, Sun Ra, Yusef Lateef, and a ton of others...

[Metal Gear Okt]

I'd say the best thing to do wouldn't be sending someone to ebay looking for Radiant Silvergun. I'd hook them up with, say, Castle Shikagami 2, Ikaruga, and Gradius V, and then work backwards and show them some of the great Cave games in MAME and some of the better DC and PS1 shmups like Zanac X Zanac, Gradius Gaiden, and and Rayforce.