Pac-Land

It's scrolling! It's a platformer! Oh my god!

Incredibly prophetic how much of the elements Super Mario Bros. would later incorporate, from the eight-world, four-stage structure, to the lakitu bombers present in the form of the Ghosts flying in airplanes and throwing miniature versions of themselves. You control Pac-Man with only three controls: Left, right, and jump, while double-tapping on a button would make him run, and in that sense jump higher. You can find occasional power pellets which, like in the classic arcade game, lets you munch ghosts for a limited time, and some parts of the stage even include secret power-ups such as a helmet that protects you from mini-ghosts.

The jumping is the most responsive and controlable that has been than in any other platformer, and each of the stages bring a new environment: Whether it's a straightforward path, a mountainside with many pits, deserts with quick sand, maze-like castles where you need to find keys and it gets dark, or (the much dreaded) ponds, where you have to use springboards and later button-mash on the right-side button to stay afloat(which is NOT COOL).

Barring the awful choice of the pond stages, this game is truly a silent masterpiece, and had it done something much more than recycling its initial stages into the 70% of the rest of the game, many people would place a firm paperweight questioning if SMB1 is really the whole inovator it's cracked up to be or not.

But no seriously, screw the ponds.

One final thing: Play the Japanese version! The graphics in the US version was slightly altered to give Pac-Man a look more reminiscent of his US cartoon, but the Japanese version is also slower-paced, which is very helpful and makes the game that much more comfortable to play. The US version is so sped-up that the faster gravity just does not sit right.

NES: The NES port came out too little, too late, in a post-SMB era when this type of handling platformers was already outdated(and it still relies on button-mashing A and B to move), and on a graphical level it is laughably reduced, although its general structure is competent. If you have the arcade version, there's no use bothering.