The Halo 5: Guardians multiplayer expansion Monitor's Bounty is out now, and it brings a lot of changes and new content with it. Monitor's Bounty is the first expansion for Halo 5 since June when 343 Industries halted their monthly update cycle.
The major update to the interface that comes with Monitor's Bounty is the custom game browser. You can now use the browser to locate and join in-progress custom games. The Xbox One and PC versions are both getting this new browser, and with this update PC, Halo 5 players finally have full access to the entire Forge and Arena gameplay experience.
There's also the usual plethora of new weapons and cosmetics, including the return of the Grenade Launcher from Halo: Reach. There is also a new "Voices of War" req pack for sale for $10 which adds Edward Buck, O31 Exuberant Witness, and Yabda the Merciless as multiplayer announcers. If you're feeling generous, you can also use the new ability to gift Req packs to get your Halo 5 friends something nice. 343 Industries is also giving everyone a Req pack that can only be gifted to let players try the new system.
For more note on the expansion, including the adjustments to Arena mode, you can check out Halo Waypoint. If you own a copy of Halo 5, the latest update should have installed all of the Monitor's Bounty content onto your platform of choice.