AdventureQuest Worlds - AdventureQuest Worlds (or AQWorlds) is an easy but very popular browser-based massively multi-player online Role-Playing game.
Realm of the Mad God - Realm of the Mad God is a best online hack and slash video game that includes pixel style graphics.
Eden Eternal - Eden Eternal is a Fantastic Browser-based, Action-Adventure, RPG and MMO video game developed by X-Legend and published by Aeria Games.
Runescape - RuneScape is 3D Action-Adventure, Massively Multiplayer Online, Role-playing, Fantasy-based and browser-based video game developed and published by Jagex.
Adventure Quest - Adventure Quest is an Action-Adventure, Free-to-play (One Time Membership Fee) Single-player MMORPG, Browser-based and Fantasy-based video game developed and published by Artix Entertainment.
LaTale - LaTale draws heavily from some other 2D side scrolling video games to provide a great fantasy MMORPG world.