Response time and strength consistency could be detected regardless of having another computer.

If a person is always playing fast moves, or playing very consistently or very inconsistently good moves, they could be detected.

- Response time

- Strength consistency within current game

- Strength consistency across all of user's games

- Is user switching windows

I bet these are already integrated in current cheat detection.

Back then the document object in javascript were way to powerful because everyone was so naive.

Internet Explorer knew/could easily infer its absolute coordinates from the origin on the desktop, would gladly serve the majority of your C: drive to any website that asked nicely enough, and a plethora of now-incredulous things.

It was possible to know if you had moved the window by dragging or by Cascade windows, had another window (this was before tabs were invented) that was being referenced nearly every turn, or even if the user had referenced an application from the Start Menu.

That was all the stuff that "wasn't" supposed to be done. The obvious, yet cat-and-mouse tricks, such as mouse/keyboard jitter, fingerprinting profiles, style/chat stylelemoetry, behavior meta-game analysis, were in their relative infancy, but were making strides.