La-Mulana

A 2D side-scroller, like the awesome Cave Story.

I'll let the official blurb wet your appetite ;)

La-Mulana is a freeware free-roaming platformer game designed to look, sound, and play like a classic MSX game. It´s heavily influenced by the classic Konami MSX game "The Maze of Galious" and anyone who has played that title will probably recognize the similarities very quickly. You play the whip-wielding Indiana Jones-esque archaeologist Lemeza Kosugi as he investigates the ancient ruins of La-Mulana in an attempt to find its treasure and one-up his father, who is trying to get the same treasure as well.

Grab it from here.