You can download the patch here: https://www.mediafire.com/file/viz0hl6jfvd2rk5 Patch a 1.0 U Headerless ROM.
This was a ROM hack created by me. It was made with the intent to just be a gag gift to Lovebird. I didn’t think it would gain any traction. What this does is globally allow the Blackout Basement light effect. There were a lot of considerations going into this. The blinking effect has a lot of small factors that even make it work! You can still see the terrain a bit, notably on snow levels, when the lights go dim. This is because the game utilizes color math. By using color math, the game just changes the intensity of the RGB hues.
Another factor is sprites for most entities aren’t rendered. This isn’t tied to color math, so I had to manually enable that. There is a routine that temporarily saves the id array, clears the ones that disappear, draws the screen, then restores all of them. Drawing the screen is the key here. Drawing to screen is done by id. This means things will still exist without being rendered!
HDMA is also a consideration. To get those mineshaft lights/squawks to work, HDMA affects the palette on each scanline.