There was a very early MMO game which leaked its server files & people started doing custom servers. There was a VERY limited scripting language for the server

There was a very early MMO game which leaked its server files & people started doing custom servers. There was a VERY limited scripting language for the server. This had some commands but missed basics like variables. However you could track the number of NPCs in a room. So this led to some rather interesting new primitives: - "Chickens in a room" became my preferred method of counting / implementing any kind of persistent global state. - For timers I would spawn an enemy and a guard. When the guard killed the enemy the timer was up. (The number of NPCs dropped back to 1). Combined these concepts to implement "dungeon instances": copied the map (as in literally copied the file) 10 times, used chickens-in-a-room to track which one players would enter, and whether you were entering the current instance or incrementing to the next was determined by the guard-kills-mob timer.