Very interesting. I don't play chess but like to observe others playing and talking about it on YouTube.

I thought about something the other day... Modern chess sites run proprietary algorithms to detect cheating by modern engines. But would it be possible for an old engine, let's say from the 70s or 80s, running on modern hardware to deceive these algorithms?

They wouldn't win every tournament but still have a respectable performance.

I've built engines from scratch. I don't think that would work at all. It's a whole extra challenge to make an engine feel like a human. The engine has to come up with its best move and then sometimes choose not to play it and play something else for some reason. There are statistical patterns to how humans make mistakes based on their level, what kinds of mistake, how big and how often. Cheat detection is less about knowing the engine and more about statistics.

Maybe a pure neural net (no tree search at all) would stand a better chance. Shockingly, those can play at IM level.

Sargon II is available:

https://c64online.com/c64-games/sargon-ii-de/

My guess is that they would be even easier to detect.

From what I gather cheat detection uses a combination of factors to determine how "human-like" an account is: time usage, webpage interactions, move quality under time pressure and so on. I think you could probably try to deliberately deceive a specific website's cheat detection with software that tries to emulate how humans play, at which point you'd be in the classic attack vs. defense arms race.

Also notice that for events like Title Tuesday you must play on a dedicated client with at least 2 cameras, so it would be significantly harder to pull it off.