Thanks PC Engine Fan X and Some-Mist!
Gun Trails is indeed very impressive; the animation and music are top-notch, and the game itself is a lot of fun. Not very bullet hell, but I hear the Gun Trails team's next shmup might be increasing the bullet density a lot.
Having 16mb to work with makes programming for the Playdate really fun, since you can offload things that would normally be too intensive for the CPU (like sprite rotations) to pre-baked images in RAM. Angel Pop also abuses the hell out of this for 50fps (max fullscreen refresh rate on the Playdate).
So far, there's only yellow, but I would love some additional colors too.
As an aside, other playdate shmups at the moment include:
Escapepion : Exerion style shmup with pretty graphics. ~5 minutes? 1 life only.
Kuro Obi: Like a shmup, but your only means of attack are the grappling hook from Triggerheart Exelica. 3 minutes, but fun and very replayable.
Made In Wired: A port of a P/ECE shmup by Jumpei Isshiki (former Compile dev, also worked on Illvelo and Rolling Gunner). It's like a warioware style shmup with 40 different minigame puzzle stage types. I ported this game because the original version seems to be lost media.
Really hoping more traditional (danmaku or not) shmups appear for the system, too.
EDIT: Changed the title to be a bit more general, since I don't think there's a playdate shmups thread yet
