Doctor Octoroc took the happy goodness that is Dr. Horrible and did a version of it as if it was an old 8-bit game. Check it out here:
There is a minor bit of music with it - so keep that in mind when you check it out.
It's only the first act so far - but it's brilliant!
I only have one nitpick - there should be one more remote access - you'll know where if you have seen the original.