wesleyk

Reminiscent of the Megaman / Megaman X games from my childhood. Megaman 2's algorithm is available as an example here: https://github.com/kpshek/mm2pwd

Demo: http://www.sandropaganotti.com/wp-content/goodies/misc/tws/d...

It's free, and also by learning with Duolingo you're helping translate the web. http://en.wikipedia.org/wiki/Duolingo

von Ahn gave a talk at Carnegie Mellon last spring on Duolingo as well: http://www.youtube.com/watch?v=cQl6jUjFjp4