Acc to Partridge's Slang Dictionary, "loopy" for mildly mad derives from "looby", meaning an idiot since C14. I cannot feel that the game derives from such an association: particularly not a connection to loup-garou; and I find the suggestion that St Vitus Dance or mustard gas would have had an influence an example of that determination to find a rational irrationality to explain every folkloric manifestation [cf Ring-a-Roses and the Plague!] ~~ an example of the phenomenon the late Peter Opie once described to me in an interview as a determination to create "folklore about folklore".

~M~