I think that’s challenging to achieve if you also want the robot to play well under time pressure.

Even if you manage to build an actuator that can grab a piece quickly but can’t break anything, the required rapid movement of the arm still can break things.

How about a magnetic base on each piece and a table built on top of a pair of xyz movements holding two magnets. That way the brain can at any time grab its piece and make a move while nudging any obstructions out of the way temporarily. It could probably made to filp the polarity on the lower magnet causing the opponent piece to topple gently when appropriate.

Seems very human proof and also exciting to watch in action.

It doesn’t even need to be that complicated. The moving pieces can move between other pieces.

For example: https://youtu.be/JhoLEbUOYlk

Neat, and very cool that they're open sourcing design and software elements. The video had me thinking that this kind of thing must have been made before. It's exactly the sort of thing they used to sell in the skymall catalog. Sure enough: https://youtu.be/mrDy0dF8aQw

> How about a magnetic base on each piece and a table built on top of a pair of xyz movements holding two magnets

Cheap chess playing devices like this have been available on the consumer market at least since the 80s.

My parents got me one from Toys R Us about 40 years ago.

The problem is that such devices are not as much of a spectacle as a big robot arm that moves by itself.

The Milton Bradley Grandmaster had that in 1983: https://youtube.com/watch?v=kEV7WRGYwGI

A small plastic tube sucking air in to lift a piece would also do well.