Very sad news, Manny's Panzer Korps and the OPFOR expansion are superb game rules that really don't get the appreciation they deserve.
He always seemed to be fighting online against gamers too impatient (or too stupid) to actually play what he wrote rather than just flicking through a book and assuming that gave them the right to criticise it.
He could look at combat at different levels of engagement, isolate just the key factors that made it unique and come up with game mechanics to capture those specific factors in a game.
Something very few rule authors can do, Bob Jones and Arty Conliffe being, IMHO, probably the only others.
I hope his family get the help they need to sort things out and that somebody keeps the Hoplite series going.