Tibia is a free to play classic 2D medieval MMORPG created by CipSoft. It is one of the oldest MMORPGs (released in January 1997) and was considered most noteworthy in its early years. For more than 10 years now, players have been visiting the world of Tibia.
Adventure Quest Worlds is a free to play 2D browser MMORPG from the same creators of AdventureQuest, DragonFable and MechQuest games. AdventureQuest Worlds is multiplayer which allows for freestyle battling with other players.