It is not clear yet if this is a MMORTS, but news comes to us of Saga's Captains of Darktide which is being made using the Unity 3D engine, and means a gorgeous 3D world in a browser playable on both PC and Mac. You can check it out at GDC 2010.

Silverload is creating one huge seamless world where players take control of a ship in the SAGA fantasy universe complete with cannon decks bellow and dragon summoning wizards up top. They are going to focus on the ship. This means even though your captain will have his own skill tree, and be able to choose from among various classes, all the action takes place at sea.

At release they are aiming to have the following features:

• A huge seamless world where tens of thousands of captains may adventure together.
• Over 200 troop types that may be used to crew your ships ranging from dragon summoning wizards to Orc snipers.
• Hundreds of cannon types.
• Over 1000 ship upgrades
• A crafting system that may be used to build cannons or the top level ships
• 3 talent trees (Defender, Commander, Destroyer)
• Hundreds of ships, with ship types for each of the above Captain trees, each with its own unique strengths.
• Cooperative questing in groups
• Epic Boss level encounters
• Player trading
• Whatever else they can fit in from the wish list