I made a crappy bot for your game. It runs game tree search (no pruning) for 4 plies and picks the position with the most material advantage. It seems to beat me more effectively than most human opponents so far, though. What it lacks in long-term planning it makes up for in taking advantage of tactical errors.

It's currently running in a loop under the name "LASERFISH SHITTY CPU OPPONENT". It never joins your games - you have to click on it.

I also thought about making a puzzle opponent that would give you unusual FEN starting positions and nearly unlimited time, but I don't want to invent puzzles.

Does the game not send a gameOver packet when you win or lose by pawn move?

edit: I figured out why it can't find any moves and crashes. It can't find any of YOUR moves if it backs you into a corner and takes every single piece. With the crash fixed, it seems to be winning 2/3 of the time and drawing 1/3 (probably some stupid logic where it thinks lasering your king and their king and one pawn is a good tradeoff)