Once, humans and robots lived together in "Harmony". Then robots had enough and revolted. The robots were too powerful for the humans to destroy, so around the world shields were put in that required certain heart rates to get through. The robots tried kidnapping people to get through the gate, but the worry caused by being kidnapped would raise their heart rate above the limit to be able to pass through the door. Most robots, trapped in their little area with no hope of escape rusted away... Except for a tiny robot in the woods who had a mind control helmet, and the patience to wait for someone to foolishly walk by. Oh look, there is someone now...
Backwards: One or more aspects of the game works the opposite as would normally be expected: maybe the controller is reversed (left is right, right is left), maybe you win lives every time you die, maybe it scrolls to the left and your character moonwalks.