This happened to me too, after getting black screen after the latest update of WGT app. I am running and older Mac with High Sierra, an older Mac OS...the newest my old Mac can handle. We have been left behind by WGT because we users of older Macs only represent 1.5% of user base, according to another poster.
Makes sense. But it still sucks to be us, aye?
MrGrapeApe:
Does anyone have any more insight on this? I dragged WGT into the Applications folder, but the same error message appears. I can't play and this sucks like Mofo McJoe.