I played several games as a teenager, but never lasted beyond November 1941 on either side. That's when the British get massive reinforcements for Operation Crusader.
As I remember, the Operation Crusader reinforcements were very nearly the size of the whole original German force. So the Germans win if they capture Alexandria before the British get the Crusader reinforcements, and maybe they can win if the original British force is on its "last legs," by November, 1941 so that the Crusader reinforcements don't give the British the advantage.
My recollection was that the Germans received somewhat more reinforcements for part of 1942, but they also have severe supply problems then. Do they have a "second chance" if they haven't beaten the original force and the Crusader reinforcements piecemeal? Or are their winning chances "bunched" before November, 1941?