An alternate take on gamified productivity:
https://www.lesswrong.com/posts/KwdcMts8P8hacqwrX/noticing-t...
https://www.lesswrong.com/posts/KwdcMts8P8hacqwrX/noticing-t...
Other features of Duolingo (the streak, the daily goal, etc.) play really well with my own intrinsic motivation, FWIW.