This is a hard question. Firstly, the lightning is controlled by the weather mask - which can be set using traxx 1.3/1.4 or if you edit the sit file. You can find a few notes on the sit file
here. But more. Graveyard is not the only track with lightning. You will see lightning on all tracks if you run them in the rain. The thing with Graveyard is that you can't run it in anything except the rain.
So far, nobody has separated the lightning from the weather. It seems to be controlled just like the sun and the moon and the rain - all of them from within the game. What I mean is, the sun appears when it's clear, and the moon appears at night, and the lightning appears during rain. Not a lot is known about exactly how these things work. One thing is certain, and that's that it is not the backdrop. Rather, it is a texture effect controlled by the game. However, we all know that these things can be altered. The trouble here is to figure out how to do it. If I was going to start playing with lightning today, I would start by looking in the sound scheme file since I suspect that the lightning is triggered by the corresponding thunder sounds. If one could de-code the weather mask value in the wav sequence I think that would be a big step toward achieving this goal. That is, if it's possible. I mean, just think. If this is possible, you'd be able to have the moon during day or the sun during night. At this point in time, I just haven't played with deciphering what is hard coded into the game and what is not.
Please let us know if you make any discoveries.
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- Phineus