Ultima Online

Ultima Online is an fantasy-themed MMORPG (Massively Multiplayer Online Role-Playing Game) played all around the world. Game servers are called shards. The game was launched in 1997 by Origin Systems. Nowadays it is owned by Electronic Arts. Like in other games, play is mostly about getting the best character.
Game play.
The game continues with game mechanisms from the original single player game "Ultima". It was designed as a kind of social and economic experiment.
Skills.
Skill are measured in percent. The game has about 50 kinds of them. Magery, Necromancy, Alchemy, Mining... The highest amount of skill is 100%, but with special items it can be raised to 120%.
Statistics.
Basic player statistics are strength, intelligence and dexterity.
Craft system.
"Ultima Online" has a huge craft system. Players can make various things from weapons to whole ships.
Datadiscs.
Datadiscs mostly add new monsters, items and maps.
OSI shards.
OSI (Origin Systems Inc., now part of EA) is the name for official servers (shards). These servers have run more than 10 years.
Shard emulation.
"Ultima Online" files can be easily modified. This ability gives a free hand to many projects. To run your shard, you need a server emulator. The EA games tolerates other projects.