Hi there,
The location of the undo button is very unfortunate! By replacing the submit button it exposes the user to the likelihood of an accidental double click; now an accidental undo.
I have requested an undo in one of my games by accident this way. Unfortunately I cannot undo my undo either!
Yes, I’ve done the same. Either the button should be elsewhere, or there should be a way to retract an undo
Yes. It’s especially troublesome on iphone/ipad.
Indeed, this happened on my iPhone; there was a delay between clicking submit and any action being taken. I thought i’d missed the button but no; just as I went to press it again it changed to undo!
Seconded!
There is an industrywide problem with mice that makes them double-click when you intended to single click. It seems that the newer mice are using cheaper parts.
Basically, is not just the iPhone that makes this a problem.
I would like to see a retraction button in addition to changing the button location anyway.
The easiest solution is to requir confirmation on the undo button just like there is on the resign button
I think the easiest solution is to move the undo button. Where the undo button appears now I think an analyse button should appear. Undo should perhaps appear under or next to that. This preserves the layout of the page when a move is made.
Otherwise the page may jump slightly after a move is made because the button disappears.
I think Undo should be on the right menu.
Exactly. If you want it, find it.
Yeah that’s a good point, i’m not sure why i stuck it where it is now. We’ll move it to the right menu 
On mobile devices, the undo button is still located very badly, resulting in frequent undo requests by mistake.
Why not add a confirmation dialog like with the pass button?
So 6 years ago it used to be undo button huh. I wish it was undo again instead of pass. Happy 2020!
I had the same problem, of doing undo by mistake.
Undo is a rarely used feature. It shouldn’t be in the main screen, especially where I would expect the “back” button to be!