NBA 2K17 will be playable for free on Xbox One for the next few days, though you'll need an Xbox Live Gold subscription to participate. Gold members will be able to download the game starting at 9 AM PST (12 PM EST) on Friday, November 18. It'll be playable from then until 11:59 PM PST on Monday, November 21 (3 AM EST on Tuesday). You can grab it from the Xbox Store or through the Gold Member area of the Xbox One dashboard.
It's the full game you'll have access to, and you'll be able to keep any Achievements you earn during the free-play period. Should you want to continue playing after Monday, it'll be on sale as part of Xbox Live's Black Friday sale that officially begins tomorrow. An exact price for the game wasn't shared, but an Xbox Wire announcement about the free event says it'll be 30-40 percent off. At least some of those deals have already gone live, with 2K17 currently listed as $42 for Gold members.