It looks like this while running: https://svkt.org/~simias/misc/wolf-floor.png
That being said if you're interested in writing something like that I recommend that you use any basic tutorial on raycasting and try implementing it "from scratch" yourself, it's pretty simple and quite fun IMO. IIRC I used this one: http://lodev.org/cgtutor/raycasting.html
A text editor by the guy that made redis, in less than 1000 lines and a lot of comments.
https://github.com/s-macke/VoxelSpace
The text in the README describes the technique very well. The JavaScript code is a little bit more complicated to read because most of the source contains the usual organizational tasks around the algorithm (initialization, keyboard input, ...). But this is also true for the provided C-code of this article.
It uses a deferred rendering pipeline and currently I am trying to get light volumes to work.