Sea of Thieves is among the very few Xbox One exclusive titles in Microsoft's 2018 arsenal, and it's due to ship on March 20. Of course, like all Xbox games it's also coming to PC, so the next closed beta – which kicks off on January 24 – is coming to Windows 10.
But you'll only get access if you either a) signed up for it last year or b) have pre-ordered the game. You'll need an Xbox Live subscription too, though that's easy enough to arrange. If you do qualify to be part of the closed beta, it runs for five days, finishing up on January 29. (Full timing details are in the announcement)
Naturally, the closed beta won't provide access to the entire game, but it should sate the curiosity of anyone keen on this pirate cooperative adventure. There are no NDAs attached either, so if you can't get access to the game, you'll at least be able to watch streams of it.
Long in gestation, the Rare title is a bit of a "shenanigans simulator" according to Steven when he played it last year.