That's what developer Eric Ruth wondered, apparently loving both Left 4 Dead and the NES. He has remade the game as Pixel Force: Left 4 Dead. This isn't a low-fi conversion, but an attempt to make the game as if it actually came out in the 80s. This means no 3D, fat sprites and a cartoon 8-bit look.
Pixel Force: Left 4 Dead is one or two player, on the same keyboard, and has two difficulty levels. There are two weapons to switch between, basically a machine gun or shotgun, and a pitifully useless pistol. Zombies rush at you if they see you, and take a few shots to kill, making it pretty hard.
You only have one life, and there are no saves. This sounds harsh, and it is, but it's also in line with the 80s Nintendo feel. Whether that's a part of 80s gaming you have nostalgia for is questionable! Never the less, the sound, graphics and gameplay really do feel genuine, so if you're a retro head, you'll love Pixel Force: Left 4 Dead.
Pixel Force: Left 4 Dead is a fun, if challenging piece of cool retro gaming that will really make you feel like it's 1986!