My sympathy all around....
I remember when we were just getting started with RPG's. I remember purchasing the "Little White Box" of D&D. I remember buying =lots= of D&D material from Judges Guild. But the game setting I knew best was Glorantha. I've always appreciated the depth of this setting. Greg seemed like he was somehow getting these messages from this other world sometimes. He knew it best - and he shared that knowledge with us. I can think of no better 'magnum opus' for Greg than his recent work on the two volume set of his Guide to Glorantha. I feel certain that it will be used for many more years. My deepest symphathies to any one whho was impacted by his passing. We shall miss him.