Dream Fall: The Longest Journey is about as close as you can get. If you like adventure games, you’ll love this one.
I gave this a lot of thought on my own, especially since my favorite type of games are RPG’s. I thought up learning different aspects of the RPG, maybe learning elements, or flying, running fast. My title for the game if I were to choose would be “DreamScape”. I have a better name for it but I am kind of saving it for a cartoon I am soon to make. =/
That an interesting idea… RPG style…
The big problem with LD related games is that they will either teach you how to LD, or they will let you feel, somewhat, what can you do in an LD.
So, how about a game in which you can’t lose,
Can’t die without wanting to,
Can “spawn” things,
Can move in any possible direction,
And can use different items, such as cars, guns, swords…
Basicly, you will need GTA with the source engine, where you are a ghost and can spawn stuff by typing their name in-game (For example, you start to fly up, and while flying, you press the letters CUPOTEA, and a cup of tea apears in your hand)
How about software that isn’t necessarily a game, but rather a repeatable routine that presents a random situation and then the user inputs how he or she would react if they discovered at that moment that it was a dream? I guess it would almost be like a flash cards sort of thing, with the question “What would you do if you discovered RIGHT NOW that you’re dreaming?” I’d buy a program like that…
Would be fun, though hard to make, such a game. 
I was working on an LD game for PC, once. 
Sadly my computer crashed, and my hard-disc was lost.
Anyway the PS2 horror game Zero 3/Fatal Frame III/Project Zero 3(Half cheesy trailer; Wikipedia Article) mostly acts inside someone else’s Lucid Dream, where the main-characters too become aware that they are dreaming (though they have no control of the dream them-self).
It’s actually a very good game. 
You should try again Painocus i would love to try it
When I was heavily into Diablo (addicted really.I would hold off on going to the bathroom so I could keep killing monsters.) I would play until I finally went to sleep and I would have like 2 or 3 diablo dreams everynight! So if you could make a game whose purpose is to teach you to lucid dream you could get more lucids faster and this would get you to the tipping point where you learn to get lucid BY being lucid so the lucid dreams would generate more lucid dreams instead of having to do all the set up work while you’re awake.Also if you want to spread the experience of lucid dreaming then a video game would really “spread the word”.As an aside the game could have tons of lucidity related info like the Senoi and the Dreamtime and so on.