What is a list of fun games to play online

That list is guaranteed to be highly biased/opinionated, so here is a list not entirely based on opinion, but instead mostly based on advertisements i've seen.

• World of Warcraft
• Star Wars: The Old Republic
• Starcraft II
• Runescape
• Digimon Battle (Digimon Battle Online)
• Xblaster
• Cartoon Network Universe: Fusionfall
• Rift

the list could go on, but there is no need to list every online game in the world.