I had my first coding experiences with Graal Online trying to make maps for it. I wanted to become a LAT (level administrator) for one of the playerworlds. The level editor was very easy to use and so was the game scripting language. It was great for creative people.
The game had a LOT of player made content. There were so many different heads, bodies, swords, maps, items, etc. When you opened the game folder, you could all the skins your game client had downloaded from other players.
There was also a local version of the Graal classic server which you could play split screen with someone. The map was huge and had all sorts of things. Good times just trying to explore it all!
Playerworlds usually had 25-200 players on at any given time, so the communities were tight-knit and you ended up getting to know everyone eventually, even the staff who were just regular players.
The game encouraged creativity since anyone could become a staff member and help shape the playerworld. Messing around with the level editor and tinkering with Graal's custom scripting language 'GScript' was my first introduction to programming, so it was highly influential for me. Come to think of it, it was also my first introduction to Linux! (Thanks Napo from AEON!)
It also introduced me to memory/hex editing. I remember searching for bench.jpg which was located near some players and changing it to cloud.jpg, causing the bench near me to turn into a cloud which then would paralyse my unsuspecting victims. Ahh good times.
Other big MMORPGs for me were Helbreath and Ragnarok Online