Tokumaru has released a ROM of his raycaster engine for NES/Famicom.
Current features:
. 8×16 pixels 1-bit wall textures;
. Up to 3 different wall colors per room (shades achieved through dithering);
. Map sizes up to 128×128 blocks (AFAIK, Wolf3D levels were 64×64);
A video in action can be seen here: https://www.youtube.com/watch?v=po69zgqyFWM