Yesterday, Microsoft announced it would be removing 21 titles from the Xbox One Game Pass catalog at the end of the month on May 31. It was unusual to see so many games removed at once, but that wasn't the end of the story. Indeed, Mad Max, Lego Batman, two more titles will also be leaving Xbox Game Pass catalog at end of May (via True Achievements)
Along with Mad Max on Xbox One and Lego Batman, Sam & Max Beyond Time and Space and Sam & Max Save the World will be the other two titles departing from the catalog. So, if you're still enjoying these games, it is best to finish up playing before the month end.
When old titles like these leave the catalog, Microsoft usually replaces them with a new lineup of games. We're still waiting on an official Xbox Game Pass lineup for June, and we'll update you with a new post when the new titles are announced.