Kung Fu Er San | Artorias

Summary pulled directly from Steam - Some text may only be applicable to Steam platform

Lee's sister has been kidnapped.
The Shadow Circus is in town.
This is not a coincidence.
Let's go rescue her.

Kung Fu Er San is a 2D retro pixel side-scrolling beat 'em up, inspired by classic games and martial arts films.
You take control of Lee Shao, a talented Shaolin Kung Fu Master whose sister has been kidnapped.
To rescue her, Lee must fight his way through side-scrolling levels full of traps, thugs, obstacles and surprises, and master his punches and kicks to defeat all the members of the Shadow Circus, a gang of evil circus artists, with crazy unique powers and fighting skills.
The path is arduous, so are the fights.
Do you think you have what it takes?

Features:

Single player Arcade mode;
2 players Versus mode;
Action/adventure levels and one-on-one fighting levels;
Unlockable characters;
Unlockable Hard Mode;
Refined gameplay;
Simple controls;
Playable with keyboard or gamepads;
Steam achievements;
Many references, gags and surprises.