I have this dream a long time ago, and I really wants it to happen again. guess I'll share with you guys.
It was a normal school day, where the class is lit pretty bright by the morning sun, yukari appears, and spirited me to gensokyo (I remember her saying some thing, but it was so vague i can't remember the detail). Then the rest is just that : I got to live in some kind of old village, learns danmaku, have a few battle with reimu and marisa and other character, I remember having some water spells up my arsenal. Then it goes random as I feel like I'm flying in rainbow course, then it went dark, and I woke up.
It can be classified as a lucid dream, i don't know. It just what my heart desire (I think), and I daydream about this a lot, then one night, it just occurred. I don't have complete control of the dream, but I can sure expect a plot line and it happens, although it's not very precise and in detail.