PirateStorm.
Pirate Storm offers a pirate-themed, browser-based Flash MMO where players can navigate the ocean, fight enemies and monsters, duel others, and more. The game is designed to offer ease of play for beginners. The game is available in several languages including English, French, German, Italian, Spanish, Turkish, Polish, and Brazilian Portuguese.
Sign up at :
PirateStorm.com
Drakensang Online.

Drakensang Online is a 3D fantasy browser hack-n-slash MMORPG that’s loosely based off of the PC game series known as The Dark Eye. Players must embark on a mysterious adventure in a medieval land that is corrupted by evil. Fight masses of gruesome monsters. Explore challenging dungeons and team up with other players.
Sign up at : drakensang.com
Call of Gods.

Call of Gods is a top-down browser game . It puts players in charge of human, elven or undead armies as they build their private fortress, collect treasures, explore dungeons and compete with other players as they progress through a colorful, high fantasy world. With inspirations from traditional turn-based strategy games such as Heroes of Might, Call of Gods keeps the same experience while adding a multiplayer element to the mix.
Sign up at : callofgods.com
Gunshine.

Gunshine is produced by Supercell. It’s a top down game, similar to the previous titles, but without the anime style. This art style is more comparable to that of Team Fortress two: a cel-shaded comic book look with enlarged bodies and smaller arms and legs. It has a modern feel, and simple class and avatar customization options. If you prefer guns and bullets over bows and arrows, this would be your first stop on the list.
Sign up at : gunshine.net
My Lands

My Lands: Black Gem Hunting is a browser-based massive multi-player on-line game (MMOG). Genre: military-economic real-time strategy game
You cooperate with thousands of players in real time: develop your city, trade, make alliances and start wars. You are also able to choose a military or a mining server.
Sign up at : mlgame.co.uk
Settlers Online

The Settlers Online is the free-to-play browser game version of the popular 'Settlers' series published by Ubisoft. The strategy game has several core features – resource production, military action, construction and development and more – that need to be managed efficiently and with tactics in order for players to be successful.
Sign up at : thesettlersonline.com