Hmm... let's see what I can remember...
Aleste (MSX)
Aleste 2 (MSX)
Aleste Gaiden (MSX)
GG Aleste (Game Gear)
GG Aleste 2 (Game Gear)
M.U.S.H.A. (Mega-Drive)
Super Aleste (SNES)
Zanac (MSX)
Zanac (NES)
Zanac EX (MSX)
Zanac Neo (PS1)
Gunnac (NES)
Legendary Wings (NES)
Recca (NES)
Gradius (MSX)
Gradius (Arcade)
Gradius 2 (MSX)
Nemesis 3 (MSX)
Space Manbow (MSX)
Soldier Blade (PC-Engine)
Knightmare (MSX)
Sagaia (Master-System)
Silkworm (Amiga)
Blast Wind (Saturn)
Coryoon (PC-Engine)
Harmful Park (Playstation)
Armed Police Batrider (Arcade)
Astro Warrior (Master System) (Well, I looped it 4 times

)
G-Darius (PSX)
X2 (PSX)
Tyrian (PC)
Creature Jungle 16 (PC)
Xenon (MSX/Spectrum)
Phantis (MSX/Spectrum) (The 1st part is a shmup game.. I finished the whole game)
Stardust (MSX/Spectrum)
Swiv (Amiga) (I remember finishing it.. but I must admit, I dont remember if I Cheated or not..)
Alpharoid (MSX)
Jagur (MSX) (Not a real shmup, but its listed in the Xenocide files, so...)
Undeadline (MSX)
Who Dares Wins 2 (MSX) (Again, not a real shmup...)
Power Strike 2 (SMS)
Twinbee Yahho (Arcade)
Darius Gaiden (Arcade)
Star Force (Arcade) (Reached Infinity stage)
Gigawing (Arcade)
That's what I can remember now... nothing here is extremely hard either. (Except by a couple of games, that could make a good list in those "Easy games to 1cc" topics

)
Games I am ashamed of have not finished yet:
Thunder Force 5 - I got to the last boss twice. I just stopped playing it for some reason.. I should get back to it and finish it at once
Zanac Neo - I LOVE that game, but my copy is pirated, and it keeps crashing from time to time, which makes me hate playing it
Sonic Wings Special - Same as TF5, I could reach last stage consistantly, then I got newer games and stopped playing it, and I just lost the hang of it. Nowadays when I try to play it again, I just suck at it too much

.
JP, you got me worried... you have 1cced Sokyugurentai and RSG, 2 games that just kick my ass badly... and you haven't finished Hyper Duel...
, I can 1life Hyper Duel easily up until the 3rd boss, and then I can't get past of that sucker. I'd think Hyper Duel would be as easy as Blast Wind.... how hard does it get later?
Edit: Removed the "Darius Gaiden is beating me" part as I have finally finished the game
