I've been looking at many of Casey's videos for a while, and recently decided to start working on the actual coding. Because I use Linux, I've been following the SDL2 tutorials, and, out of curiousity, recently decided to see how the recent code runs.
I've cloned the sdl repository, copied the cpp and data folders to the right places, patched the patch file, ran the scripts and this is the odd result I get:
I doubt this is a problem with SDL2 because it appears you are missing the handmade hero assets. Make sure you have placed the assets in the right directory that the game looks in for them.
For example on day 260: https://youtu.be/wklr6ogongg?t=59 (00:59)
The problem is that multi-threaded shared OpenGL contexts simply doesn't work. Casey has said that it should be removed or changed (to PBO).