[me_bx]

The game 'Whentaken' [1] follows the exact same concept.

Just mentioning in case people are interested in alternatives / slightly different UX.

[1]: https://whentaken.com/

[JimDabell]

Also whichyr: https://whichyr.com

Discussed here: https://news.ycombinator.com/item?id=43715024

[motoxpro]

whichyr is awesome. I feel terrible about myself that I am systematically below average.