There's a mathematician that figured that there's 10^120 possible chess games, as a lower bound. https://en.m.wikipedia.org/wiki/Shannon_number#:~:text=Shannon%20showed%20a%20calculation%20for,a%20Computer%20for%20Playing%20Chess%22. That's a 1 followed by 120 zeros for just the number of possible games. With this method they'd have to manually go through every move for every one of those games. If we say a game lasts 30 turns on average and they'd take 1 second to code each turn (realistically it'd be longer) it'd take 6.9*10^109 (69 followed by 108 zeros) times as long as the age of the universe.