The source is available on github to eyeball. I've had criticism on previous years that it is hard to figure out the structure of my obfuscated code, so this year I made sure that the if statements were easier to see and hence understand the flow of the code.
This year I've snapped up all my seasonal obfuscated C programs and put them into the snap store as the christmas-obfuscated-c snap.
Below is a video of the program running; it is all ASCII art and one can re-size the window while it is running.
Unlike previous years, I have the pre-obfuscated version of the code available in the git repository at commit c98376187908b2cf8c4d007445b023db67c68691 so hopefully you can see the original hacky C source.
Have a great Christmas and a most excellent New Year.