This is an great video by Brian Provinciano explaining how he developed the NES prototype that eventually became Retro City Rampage (available now on XBLA, PSN, WiiWare, and Steam). In the video, Brian shares tons of insights into the constraints of NES hardware and the heroic effort to make a complex game for it. It’s a must-watch for fans of homebrew.
Here’s a link to NESHLA, the NES assembler that he wrote for the prototype.