"Now, I understand why so few companies have attempted to develop a life simulation game. The challenge isn't just additive the more you try to build—it's exponential. At a certain point, finding bugs in this vast world we've created feels like playing tag with invisible ghosts."

He's not bragging; it's honesty. I'm thankful he is sharing the experience. I know totally what he's talking about. I remember trying to make a simulation of reality in the wc3 map editor in elementary school. Add the weather so the plants grow. Tie growth variables also in to deer eating them. wolves eat the deer. So everything needs hunger variables. But already we start having the 'exponential growth' he is talking about: because what about the Weather and the Deer? And the Weather and Wolves? Add aspect of the world for one type of object (weather for plants), and suddenly you have to figure out how or whether it relates to everything else you have (Deer and Wolves). Now let's say we add villagers and Structures. Every time we add something, we have more nodes to consider the interrelations of.

It's easy when there are few systems and few types of things (like a cardgame of creatures with atk and def), but it escalates quick and does exactly what he's saying the more systems you try to accurately include and farther toward 'full life sim'.

So im just a noob, but I see clearly this is what he is conveying to us. (probably cuz i tried a similar path in elementary school. if i remember correctly i ran in to this same issue, scale was too big too big project and i switched to something else. it exponentialed quick; just like he says)

edit: i bet he wasnt brave as much as did not forsee the exponentialness aspect and wanting to aim high caused him to fall in to it