Error loading Endgame Combat on startup; Renai Transportation causes Endgame to load a nil value for "braking_force" which causes Endgame Combat to not load. Neither mod has each other set as incompatible but disabling Renai Transportation fixes the Endgame Combat errors.

That's weird, Im not sure what breaking_force would be broken since I don't add any vehicles or anything. Can you copy the crash message you get?

Failed to load mods: EndgameCombat/prototypes/overrides.lua:93: attempt to perform arithmetic on field 'braking_force' (a nil value)
stack traceback:
EndgameCombat/prototypes/overrides.lua:93: in main chunk
[C]: in function 'require'
EndgameCombat/data-updates.lua:6: in main chunk

I think it may have something to do with the "train ramps" interferring with the "braking force" research in Endgame Combat.

It seems to be a crash from their end but I think the problem comes from an invisible "ghost" car that I use as a guide for the trains as they jump. Since it's just an invisible guide that should be essentially frictionless, I don't think I assigned it a "breaking force" which endgame combat is looking for. I'll have to try adding one and seeing if it loads without error

So from what I could find Endgame Combat changes the properties of some things including trains. The problem is that not all trains have the same properties like braking force. When I added braking force to an invisible "guiding" train used in my mod, it then crashed because that train didn't burn fuel to run, which I guess is another thing Endgame Combat tries to modify. I tried running the game without my mod and with endgame combat and a mod that adds electric trains and the same problem happened. I think the best way to fix this properly is for endgame combat to add some checks to make sure it's only trying to modify trains that actually have all the properties it is trying to change. So unfortunately this isn't something I think I can fix