Popular game developer, Bungie is planning to mark its upcoming 20th anniversary by holding a massive fan event including a auction of the memorabilia.

The event, which will be organized from June 23 to July 7, will offer fans a chance to get some of the very rare objects from the Halo universe. For the fans of the Microsoft’s flagship videogame, the studio is also planning to unveil details f its first cross-platform creation at the event.

The studio’s official website said, “We’re going to tell you, in explicit detail, exactly what Bungie Aerospace is all about.”

All the proceeds from the auction will go to Child’s Play and the Bungie Foundation.