Pleased to hear it made you smile :D
i was responsible for the lighting/lightning. its a canvasshader and its opensource. i made it last year and didnt have the chance back then to use it for something other than the example. This year i really wanted to use it and i have do admit i have no clue what i was thinking last year when coding that abomination.
its a convoluted mess and drove me mad cause it was very hard to use and i will rewrite it at one point, but if you are interested this is the shader https://godotshaders.com/shader/dynamic-glow/
This is the room in its full glory btw without the shader applied.