I couldn't play the game because of hardcoded movement keys.
I'm using Colemak layout, and I'm sure Dvorak people would feel the same.
My hopes were raised when I saw the keyboard type dialog, but dashed when I looked at the options.
Would recommend a text change: 'keyboard type' to 'keyboard layout'.
And it's also possible that a game like this directly grabs input in a way that an extension couldn't intercept. Web dev is really not my thing.