Why? As the name says, it is a fancier version of i3lock which is in the repositories. I've seen it in action and it looks awesome.
Open source: yes
For those packaging this: I do not want a separate fork of i3lock in the repo. Please change our i3lock to use the i3lock-color fork that is linked in the i3lock-fancy GitHub README. Also the binary needs to change from lock to i3lock-fancy or similar, I do not accept lock as a valid binary name because it's too generic.
So I got this response from PandorasFox:
There'll be some leaks reported in Valgrind.
There's some discussion in i3#168 - this is sorta intentional. We can do some cleanup at exit, but it complicates the code and doesn't really matter that much, since the OS handles that memory anyways. There's no leaks that occur more than once (i.e. all the leaked memory is only leaked once, so it's less of a leak and more of a "not bothering to clean up memory at exit, to keep the code cleaner/easier to maintain").
i3lock-color issue: https://github.com/PandorasFox/i3lock-color/issues/70
i3lock pull request: https://github.com/i3/i3lock/pull/168