Original Zelda prototype found...

[CM30]

Yep:

http://forums.lostlevels.org/viewtopic.php?t=2471

Apparently, it's a beta of the original game, complete with different enemies and such. Nintendo supposedly made the game harder between the beta and the final version.

 

[Ev!l Hydr490]

I think that nintendo didn't want the entire game to be a complete push over. That could be why they changed the game.