Sprybug at the Atari Age forums published an Atari 2600 version of Super Mario Bros. with 16 levels, world bosses, pipes and even flagpoles.
The collision detection with the playfield blocks isn't 100% perfect, but it's close. Still something I have to work on if I have the cycle time to. So, have fun, and yes I included music and sound effects.
An amazing feat of economy and skill — also check out Halo 2600. [via Indie Games]