In the third episode of the game, you just learned that you also are a weapon half human and half robot. Angry with your human creators, you turn against the only humans you have at hand: the soldiers. Destroy everything you find on the way.
Use the A/D keys to move to left/right; W key or space bar to jump; S key to crouch or slide while you move. W/S keys to go up/down the stairs. Click to shoot in the direction signaled by the mouse pointer. And the K or L keys to restart the level.