Microsoft's buccaneering simulator, Sea of Thieves, already has 10 million players on Xbox One and Windows 10. The company announced that the game is coming soon to Steam, adding to an already large stable of Microsoft games on Valve's platform, and allowing existing Steam users to connect more easily with friends. The game, which was developed by Rare, challenges players to complete voyages across the open seas. What makes things more interesting is the fact that crews can run into pirate ships manned by other gamers -- and attempt to plunder their booty.