Microsoft and video game developer 343 Industries are delivering on the free download of Halo 3: ODST and remastered Relic multiplayer map that the two promised to users who stuck with them through the somewhat disastrous launch of Halo: The Master Chief Collection.

Xbox One users who were eligible to download the new addition to the Halo: The Master Chief Collection campaign began receiving codes to download Halo 3: ODST overnight. At the same time as Microsoft was sending out codes to those who’d played Halo The Master Chief Collection before December 19th of last year, 343 Industries was updating Halo: The Master Chief Collection for compatibility with the add-on. Xbox One owners need to redeem the code on Xbox Live, and directly on the Xbox One is best since it can be triggered directly from the message.

Users have exactly one month to redeem the code that they find in their Xbox Live messages. After June 30th, anyone who hasn’t taken advantage will need to contact Microsoft’s Support Forums to get help downloading the content. Halo 3: ODST is available to those who don’t meet the requirements for $4.99. Of course, the add-on requires users to have a digital or disc copy of the actual game, according to Halo Waypoint.

The extra Remnant map is coming to everyone as a free add-on in today’s update. The multiplayer area is a remake of Relic, a map that came with Halo 2.

Arguably, Halo 3: ODST had the best campaign in the serious. It takes place in a darkened New Mombasa. You play not as Master Chief John 117, but The Rookie, a relatively no Orbital Drop Shock Trooper.