The game above is a very simple shooter. At the moment it requires a keyboard to play so most tablet users will not be able to play the game at the moment (sorry). You are the person on the bottom and must shoot the person on the top before he shoots you. Start the game by pressing the space bar (joystick button on Atari) move left and right using the cursor keys (joystick directions) and fire with the space bar.
For those of you interested in how this game was created, there is a Making a Simple 2600 Game article