the Rain
I think the first robot planed it all.
Walls were built to imprison people in, not out. On the ninth day, the robot got the knowledge that human extinction is coming and he is the next step of evolution. he then made a plan to make more robots (after 22 years). it's a plan that will only start working after 22 years. the firs part is one robot going to the desert (the one at the ending). then more robots will start "waking up" and get awareness so they could Collect materials like batteries, for example and bring them to the robot in the desert. then they will go into the next stage which is losing the The human form (Building the bug robot, and removing the human face mask as we see in the end). After the movie is over, the rest of the robots will join robots in the desert and begin to live there (after all human will die). the robot is saying something about the deadly rain, as if he thinks it is Fate.
it's a Very smart film and fun to see!