Super Mario Brothers, once upon a time a very popular & addictive game developed by Nintendo is now available as "Full Screen Mario" as a on line game.
Anyone with fully HTML 5 web browser can play the original levels, play through some of literally millions of possible random maps, or create your own using the level editor for free.
According to the site this whole project is open source and free. No registration or no installation, only need a web browser with HTML 5 support.
Visit :- http://www.fullscreenmario.com/