I changed everything back to max view, deleted the floor, walls and stuff.
Same thing, debug crashes but game will run fine.
I save the game folder on an external hard drive every few hours when game is fine with no problems.
I copied the known good game in.
Debug works fine.
So far I have my texture in game and the stairs and debug works fine.
I will keep adding what I did before and on each step debug but I didn't do much for it to act like this, just normal level making stuff.