In the beginning, it was just a game. One we've all played numerous times: select the squares with a stop sign, enter the text below, reassemble the puzzle — and check the box declaring, "I am not a robot." Yet, every time we select images determining whether what we see is a cat or a croissant, we end up working for  Big Tech . When Guatemalan computer scientist Luis von Ahn first proposed the idea of "games with a purpose" (GWAPs) in 2004, his goal was to harness human brainpower so that computers could learn from it. His idea was simple: Get humans to solve tasks that are trivial to us but difficult for computers back then, like labeling images, transcribing text or classifying data. And what better way to make people work for computers than by turning labor into play? Get rich by letting others work for you  Von Ahn first developed the ESP (extrasensory perception) Game: Two players were randomly paired and shown the same image but could not communicate.…