A great add-on for playing chess whenever you want. Replying to "it just being a picture of a horse", the problem might either be that it is keyboard-based: the mouse doesn't do anything in this add-on. Or it might be that it sometimes crashes. That's quite a big problem. When that happens, I remove it and add it again, and all should work. The settings for the keys are found at Add-ons manager > Chess (preferences).