Excerpt from [wikipedia]:
“Cave Story (洞窟物語 Dōkutsu Monogatari) is a freeware platform-adventure video game released in 2004 for the PC. It was developed, designed, andprogrammed over five years entirely by Daisuke Amaya, art-name Pixel, in his free time. The game features classic 2D platform mechanics and is intended as an homage to the classic games that Pixel played in his youth, such as Metroid and Castlevania.
The game focuses on an amnesiac silent protagonist who awakens in a cave. Through his explorations, he discovers a plot by the Doctor, a megalomaniac who intends to force the inhabitants of the cave to fight for him in his bid to conquer the world. The protagonist is thrust into the position of savior as he endeavours to defeat the Doctor.
Cave Story 3D is a remake of the original game with 3D graphics. The game was released as a full retail game on November 8, 2011 in North America and November 11, 2011 in Europe. Initial promotional screenshots showed Quote and Balrog as clay-like models floating around in a 3D environment. The game design has been completely overhauled to match the 3D capabilities of the Nintendo 3DS, though gameplay remains the same. The game also has a ‘Classic Mode’, which lets the player play the game using the original Cave Story’s character sprites in the new 3D environments.”