Microsoft's $10 per month Xbox Games Pass subscription service will be seeing the first significant reduction in its game library at the end of May. That's when 21 available titles—primarily backward-compatible Xbox 360 games—will be rotating out of the service.

Microsoft has been adding seven to ten games to Games Pass every month since its launch last June, bringing the total number of Xbox One and Xbox 360 titles subscribers can download to over 170. Only a small handful of previously available titles have been removed during that run, including WWE 2K17, NBA 2K17, and Metal Gear Solid V.

Industry watchers (including yours truly ) have been referring to Games Pass as a "Netflix for Games" since before its launch. But this is the first real sign that the service will mimic Netflix's practice of regularly cycling movies and TV shows in and out of its selection month to month. The end of May will represent exactly one year since Games Pass' full launch, suggesting that expiring year-long licensing agreements with third-party publishers could be behind the latest reductions.

While the bulk of Games Pass' selection is still made up of legacy titles at least one year old, Microsoft committed in January to making all of its first-party exclusive titles available to Games Pass subscribers on launch day. That likely helped Rare's Sea of Thieves reach a critical mass of two million players after a single week back in March, and it could help attract attention to State of Decay 2 and Crackdown 3 around their planned launches this year.

Games Pass subscribers can purchase any of the departing games (which are listed below and in a "Games Leaving Soon" section of the Games Pass interface) for 20 percent off list price, maintaining any progress stored in save files if they do. Subscribers may also be able to extend their access slightly by leaving their console in Offline mode, using a 30-day grace period before the service requires a server check to maintain access.

The titles leaving Xbox Games Pass at the end of May are listed below (all games are backward compatible Xbox 360 titles unless otherwise noted):