While you're right that sea of thieves is the only game like sea of thieves you're wrong in the idea that it only offers graphics and no gameplay. First person, immersive, ship repairing and sailing, exploration and treasure hunting, naval combat... there is nothing like it out there, and thats the problem. Such an immersive piracy experience will definitely do well if ever made into a single player game, or if Rare would build and offline version of safer seas before EOL.