Reading Gwen's article reminded me that Asheron's Call was the first MMORPG I played that supported random weather and regular seasons. Primarily, it sparked the memory of realizing that we all went inside to chat during the rain which fell in ranges of a few minutes to several days in a row. The particle system was a bit primitive; so drops did occassionally fall through the roof and even through the upper stories. We didn't mind hunting in the rain; but chatting, shopping, et al was relegated to "dry" interiors. The effect was persistent enough that conversation paused every time lightening "struck" by flashing a momentary brightness in the sky. Rain was replaced with snow during the winter months. Nobody minded standing around in the snow; however, fireside chats became increasing popular in the early calendar months.

Seasons were an integral feature of the game as they offered variations to familiar venues, were incorporated into the ever evolving lore, and offered related loot and purchasable items that might, or might not, be repeated the next year. The resulting world of Dereth seemed very tangible, even plausible, based on these rather simple manipulations. My favourite effect, of course, was the changing foliage in the trees and grasses.