What is the most accurate estimate of total possible number of chess games

Question

What is the most accurate estimate for the total possible number of chess games. I already know about Shannon's number, I'm just wondering if there's anything higher than that.

Answer 1

On the Wikipedia page for Shannon's number it states

Allis also estimated the game-tree complexity to be at least $10^{123}$, "based on an average branching factor of $35$ and an average game length of $80$"