Touhou DS

[Monkeypro257]

There was a thread of this if I can remember. (Made way back then though)
How do you install the game into your . . . well I actually have a 3Ds. (Can it still work?)

[Sparen]

Considering that Touhou games have enough trouble running on Linux and Mac, I'm pretty sure that porting to the 3DS would probably not be optimal for performance.

Not to mention the split screen.

[Jirachi]

There's some app that you can program simple games into, idk if it'd be possible to make a Touhou lookalike. They made  a Flappy Bird one, but they can't even be compared.

[Ranko Hoshino]

Touhou DS is its own fangame, though running it on a handheld would require a flashcard. Those tend to not work with the 3DS anyway because of firmware updates.

[Jirachi]

Those tend to not work with the 3DS anyway because of firmware updates.

Supercard DStwo usually updates its firmware within a short time after 3DS updates and never requires hardware replacement. They are quite expensive, though.