Is it legal to make a game based on a movie?

Yesterday I had idea for a new Pokemon fan game, the fan game was going to be based on the movie "Blade Runner", it would've had the same concept and the name "Blade Runner" in it and now I'm wondering if this is legal or if I had to face copyright for the name and concept of the game.
What do you think?
Is it legal or not?
Usually you would need a license to do that, but if you say it's a fangame then maybe it wouldn't be so bad. Either way it's murky water so I'd say try thinking of a new concept.
If you're making fangames anyways, I don't see why not. We're already in murky legal ground as it is.
So I might do it, but I'll to it later cause now I'm already working on other fan games.
I'm just gonna wait until someone says that I can't and I'm gonna take it off my list of fan games to do or he says that it's not a problem and I'm gonna keep it in the list.