Super Mario Bros Java is a free open-source recreation of the arcade classic.
The program arrives ready-to-run on any system with Java. It's not even archived - just double-click Mario.jar to begin.
A startup screen gives you options to run full screen or in a window, and with or without audio.
After that, everything works more or less as you'd expect: arrow keys to move, X to jump, Z to fire, and so on.
There's also an optional patch which should allow the game to be played with a gamepad. We didn't try this, but check out the developer's site if you're interested.
There are no great surprises here, but it's fun to play for fans of the original, and runs easily on anywhere with Java 1.4 or later.