EDIT: All articles are now up, see below for links!
So, I've been working on a game again (which now has a name: Dank Tombs), and it includes a really swanky real-time lighting engine. Working on it was a blast and I learned a lot of good stuff when optimizing it, so I decided to clean up the code, share it here and write a series of posts on it so that others can benefit as well :).
Here is part 1,part 2, part 3 and part 4 of the write-up - if you have an hour, you can read them all in one go :).
This is just a demo, so most of the cart is showing off the tech.
Controls: (O)/(X) change the light radius, d-pad walks around
If you want to explore the cartridge for yourself, the best place to start from is probably _draw() - it references all the interesting stuff and clearly shows what order things happen in.
The code is under a CC-BY-SA license, so feel free to repurpose stuff :).