Support this , sounds cool
Here some suggestions
-You could as said above try to make some kinds of challenges to get lucid , and real education about it , like the player learns more about ld’s because that would be the goal , to become an very experienced Lucid dreamer in the game.
-When you first start off , you would dream a normal dream , about something , and then you should recognize something wrong , and realise it is a dream.
Then for there on you would have to try to keep your lucidity , there could be some kind of “Lucidity meter”
And you should be able to create things , change landscape or stuff like that and the higher experience of lucid dreams you have the more things you can change in the game.
I know this sounds pretty much impossible to program all of those things but if you could it would be the best game ever