It's an interesting idea, but I'm unconvinced that a community effort can produce results (in this case, films) superior to that of a highly skilled artist. Has such a system worked in any other medium? We have the technology available now to collaborate on books on a massive scale, but are there examples of this happening and succeeding with results that rival Kurt Vonnegut or F. Scott Fitzgerald? Similarly, a GitHub for music is certainly feasible with today's tech, but I don't think this recipe guarantees results better than a small dedicated group of artists like Radiohead or Nine Inch Nails or <insert favourite band here>.
Don't get me wrong, I think the system you're proposing would be fascinating and could produce interesting material, but sometimes great artists produce their best work when every aspect is under their control.
At the time of The Godfather's release there was the same mountain of crap in cinemas that there is today. It's easy to look back on "the good old days" and conclude that the quality of modern filmmaking has decreased, but you'll be ignoring all the other junk that made it to the silver screen. Like any medium, 90% of what's produced commercially is garbage, but future generations will enjoy the films of P.T. Anderson, Tarantino, the Coen Brothers, and countless other artists working today and say "they just don't make 'em like they used to."
Also, since Taxi Driver by Martin Scorcese was mentioned, take a look at his latest film Hugo. I think you'll agree it's every bit as good as his earlier work.
The game is decently fun, but it was the art that sold me. The voxel style looks like one of those themes that developers rocking a low budget can pull off beautifully.