For a good selection of Mario games, go to Mario Games 1.
Another good site, Triplets and Us, offers a nice selection of 80's games, including Super Mario Bros.
Just ensure that you have the proper files installed on your computer, so you don't have to wait when you get the urge to play Mario Brothers online.
This means they are original creations using the Mario characters.
The atmosphere and graphics may resemble other Mario games, but the actual gameplay might be something totally different.
