Yeah, every possible combination of checkers moves has been simulated and analyzed. We know everything there is to know about playing checkers, there’s no new strategies to discover. We can write an algorithm that will ALWAYS choose the best possible move. You may have independently done that with Tic Tac Toe. It’s not possible to do with chess. The number of possible combinations of moves is astronomical; if we used up every atom in the observable universe we couldn’t write them all down, so there might be revolutionary new strategies that remain undiscovered, and that will never not be the case.