joshi tm: Black can only draw if their king can reach the 8th rank immediately after white does. This was not possible in this position so there is no reason for black to get another move. I think this shows the script is enforcing the rules.

rod03801: The black knight is pinned: if it moved the bishop would put the white king in check, which is illegal in this game - very counterintuitive for a chess game! Sort of like a reverse pin! :-)

Fencer: I often like to play Be4 as my 1st move, although I can't say if this is the best move or not! As black I usually reply to this move with Ka3, protecting the rook.
Thanks for introducing this game, I think it's a great addition! :-)