Xbox Game Pass Ultimate, a CNET Editors' Choice award pick, offers hundreds of games you can play on your Xbox Series X, Series S, Xbox One and PC or mobile device for $20 a month. A subscription gets you access to a large library of games with new titles added every month -- like Call of Duty: Modern Warfare 3 -- plus other benefits, like online multiplayer and deals on non-Game Pass titles.

Read more: Xbox Game Pass: Which Plan Is Right For You?

Microsoft recently brought the Mafia series and other games to Game Pass Ultimate, and the company is adding these games, too.

Call of Duty: Black Ops 6 early access open beta

Airdrop into the next game in the popular Call of Duty franchise now. Ultimate and PC Game Pass subscribers can explore new six-versus-six multiplayer maps and use all-new weapons and gadgets in the early access open beta of this game. Subscribers can also earn in-game rewards that carry over to the full launch of Black Ops 6 on Oct. 25.

Atlas Fallen

Take on legendary monsters using devastating powers in this action RPG adventure. This version of the game includes the major update Reign of Sand, which brings new enemies, a reworked campaign and new voice acting to the original game. The highly anticipated New Game Plus mode lets you play the game at a higher difficulty while keeping all of your items and experience.

Core Keeper

Craft, build and explore a dynamic underground world filled with adventure. This top-down sandbox game is reminiscent of games like Minecraft and Terraria and can be played in single-player mode or with up to eight others in co-op mode. So get ready to dig through mines and caverns and uncover ancient secrets that haven't seen the light of day in years. 

Star Trucker

Haul cargo, trade items with other truckers and explore the ultimate open road: outer space. Take the driver's seat in a rocket-powered big rig and cruise the hyper-highways as you deliver cargo across the galaxy. Customize your rig, gossip on your CB radio with other truckers and enjoy your view of the stars.

Games added to Game Pass Core

Game Pass Core ($10 a month) offers subscribers a small library of games, and Microsoft added three games to that library. Here are the games Core subscribers can access now:

Games that left Game Pass

While Microsoft added those games to Game Pass, it also removed three others. So if you want to finish your campaign or any side quests, you'll have to buy these games separately now.

For more on Xbox, here's everything to know about Call of Duty: Modern Warfare 3 on the service, other titles available on Game Pass Ultimate now and our hands-on review of the gaming service.