Ok, but maybe the distribution of pieces are different as well as their placement and the game is being played by 6 year olds rather than experienced players. 

That’s like adding entropy, but not exactly. The game itself would be similarly limited to common games, while guessing which game is being played converges to impossibility.

Undisciplined

What if you start a game with a non-standard board configuration, though? Now your low entropy midgame snapshot won’t look quite so chessy, despite having no more entropy than before. What would make those keys easy to find?

probably still quite predictable. Shuffled backrank (Chess960) only has 

 fresh starting positions. Enough to confuse humans out of opening prep but not much for machines. You'll still end up in pretty regular, 

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bitcoin_beginners

[ELI5] How does low entropy hurt security?

> What if you start a game with a non-standard board configuration, though? Now your low entropy midgame snapshot won’t look quite so chessy, despite having no more entropy than before. What would make those keys easy to find?

probably still quite predictable. Shuffled backrank (Chess960) only has _959_ fresh starting positions. Enough to confuse humans out of opening prep but not much for machines. You'll still end up in pretty regular, _well-trodden_ middle games I'd think.