Ikaruga - Dreamcast (you can play with an emulator). Another japanese title. This one is a bit weird. It has an iteresting mechanic centered around switching the colour of your ship between black and white. You absorb bullets that are of the same colour as your ship, while the opposite colour kills you.
You forgot the final twist: you do double-damage against opposite-colored ships, so there's the reward to go with your risk. The time saved, given how elaborate, hypnotic, and deceptive the fly-in and fly-by patterns can get, also plays into the focal-point of scoring: a "chain" system where you get an exponential multiplier increase for killing enemies "in threes" (B-B-B, W-W-W, etc.)
It's slow and "easy" on easy, faster on hard, and on medium throws in the twist of opposite-colored enemies exploding into opposite-colored shrapnel that opposite-colored fucks you up.
Really thoughtful game, the opportunity for fantastic teamwork in co-op (planning color / side switches, playing "you cover I'll fire" etc.) Bullet-hell purists just fuckin' hate it because it wants to be played and enjoyed in a different way, by more people. Don't listen to them: it's like a really dedicated Battletoads fan bad-mouthing SMW.
It's also by Treasure. You should play
all of their shooters. Including
Bangaioh, which mixes directional shooting, gravity, and just a little bit of platforming.
But my second favorite for NAOMI / Dreamcast is definitely
Zero Gunner 2, which uses its pivoting mechanic in a great way, where you can either unravel the puzzle of the "optimal flythrough," desperately react in the nick of time, or screw yourself over a thousand times by flying backwards into a laser beam.
(start at 4:20 for some great examples... why no "t=4m20s" with the WYSIWYG embedder?)
Everybody needs to be occasionally reminded of the
Kenta Cho experiments (check the Windows section for stuff that even comes close to bordering on tradition.) My favorites of his are:
rRootage (an infinite boss rush with many "familiar" game modes to choose from)
GunRoar (a boat-based shooter -- pretty clearly meant to be played with one stick for steering, one for shooting)
Tumiki Fighters (pick apart enemy craft piece by piece, catch the pieces before they fall and they stick to you = variable firepower and a few layers of potential shielding; both very procedural and well-collisioned)
Noiz2sa (just good, tight, clear, and simple shooter dedicated to pattern traversal -- holding a button down gives finer control)
They're not without their flaws, but they're
really, really good. That said, I obviously have a soft spot for different and/or mechanically interesting shooters.