Protag is still Kirby but with a small hitbox, Touhou characters as similar ball-shaped enemies akin to the sprite similarities of Patchcon,
Why do I start thinking of Yukkuris?
Yukkukirby would be awesome, though.

Personally, I've been thinking something along the lines of a SNES RPG. A magical SNES with way more memory and an improved satellaview.
Plot: It starts small(A minor incident), and along the way it gets more and more out of hand until something threatens to wipe out gensokyo or the entire world.
Maribel and Renko would be the tutorial and start menu goons, explaining everything to you and commenting on the bonus material(CGs and extra scenes and music and stuff).
When you start, you choose a team you'd like to play as. Some, like, the ghost team or the oni team, are just a duo who can team up with other youkai. Others, like team nine or the hell team(Satori, Ustsuho, Koishi, and Orin) can't recruit more than one more member, but they'll sometimes split up and you can choose what character's path you'd like to follow. Naturally, since it's hard to cram all the characters in, some extra teams will be offered via DLC.
Oh, rite. There is a dating sim option, too. You can either romance a youkai girl who's not doing any fighting, or you can romance two people on your own team. Making two people on the same team fall in love will be harder, but will benefit the gameplay-Like, extra items if Yuyuko listens to Youmu's eye for finding things. However, similar effects can be acheived by upping the "freindship" bar.
Flandre? Secret character. You can recruit her upon beating the game once and investigating SDMs basement. Beat the game with her in your party? Congrats, you can now play as her and find out what really happened during several subplots and a little bit of the main plot. It will be harder, though, and you can choose a team to team up with during the game. This mode is called EX stage.
It's going to be like most Touhou games, first we fight two small fry, later we fight a medium boss, then three stronger ones.
Except for the fact that the dungeons will be around two or three between each boss, and they'll get harder progressively. The mini-bosses in the dungeons are established Touhou girls that aren't playable, like Kisume, Kanako, or the Aki sisters. Some bosses will go live somewhere in Gensokyo so you can romance them after you'd defeated them. Though, whom you can romance is limited by the team you are on, so no crack. Except for the occasional one.
If you didn't choose to play as team nine, they will be the goldfish poop gang.
I've got several scenes in my head, like team nine sitting in a tree watching the moon, preferrebly in the middle of the game, after they understand that this is serious, people might die and never come back. If you've managed a romance between the team members, the CG will be altered to have those girls holding hands. This would be an important part of character development for team nine, since they've never had to deal with death before, and Cirno would eventually think of the frogs she's frozen, and Suwako before concluding that the frogs were Suwako's friends. She starts crying and the others comfort her. "B-but you can't promise not to die! It could happen, anytime.." "No, but we'll turn into stars." "Yeah! Yes, we'll be stars, OK? And you can ask Eirin and maybe you can go see us someday." "Whatever happens, we'll always watch over each other, OK?"
In reference to that scene, the end credits will have a scene where Cirno is making little graves for all the dead frogs, and Suwako blesses her for it.
Another one would be the shrine team also realizing that this shit is gettin' serious, beacause the Shrine team from the beginning has three members. Teams consist of two or four memebers. The characters are Sanae, Reimu, and Rin Satsuki. They've teamed up with team nine shortly before the moon-scene, and Rin dies cruelly by the hands of the stage 5 boss. If you choose to have Reimu or Sanae romance her, she'll die in thier arms, followed by a desperate "Hey, Rin..W-wake up.. R-in-" And there will be a funeral, that you'll have to go to no matter what team you are playing as. Yuyuko will be there, but without the appetite for once. Suika will be slightly teary-eyed and nearly sober, and offer a crying team-member some sake. "H-here. It'll make you remember the, the happy times.." Team nine are too shocked to say anything, Yukari will comment on Wriggle's lack of expression as "I guess boys don't cry, do they.." and everyone will disregard team nine's seemed indifference as "They're really too young to understand, aren't they?" Keine will do her best to explain to them, being the teacher she is. You can also comfort the girl of your choice at the funeral.
The beginning of the Prismriver route would have them fighting Kana Anaberal(They're investigating a wierd sound that seems to have started living in thier mansion) and having her join them over a heartwarming cup of tea. "Oh, thank heavens.. I can really stay? Sorrt, it's just- I'm so used to being a nuicense. "
Remilia would be an optional partner for a few of the teams, but when she's with Sakuya and Meiling(The SDM-servants team), a monster that is nothing short of an eldritch abomination might appear, and Sakuya will react by trying to cover the mistresses eyes.
Also, keeping yukkuris would be an important part of gameplay. You can harvest yukkuris and eat them, or chuck them at foes, and you have a special yukkucage for keeping them. You can play with them, and different kinds of yukkuri are found in different parts of gensokyo.
...Sorry for the textwall, gaiz. 0.0 I got a little carried away, ^^;;