microsoft[.]com/en-us/p/xbox-game-pass-pc-games/cfq7ttc0kgq8?activetab=pivot%3Afaqtab
xbox[.]com/en-US/xbox-game-pass/pc-games
First off it requires the May update of Windows 10, v. 1903, and the Xbox app, now in Beta. It will apparently cost $9.99/mo. eventually, $4.99/mo. while in Beta, & $1 for the 1st month as an intro offer. Like Xbox Live Gold, there will probably be 3 & 12 month cards with activation codes sold for a discount.
The game pass gives you access to the current month's games -- for the Xbox there are 100, but I don't see a number for the PC. If a game isn't included the next month, you can't play it unless you buy it outright. And you can only play the games if/when you have a currently paid subscription.
Of course if it's all worth it or not is up to you, but for $1 for the 1st month, my guess is it'll be hard to say no.