Frictional Games today announced that Penumbra: Requiem is now available for Mac and Linux systems. Penumbra: Requiem is an expansion which will tie up loose ends from previous installments and as Philip progresses he will encounter various characters from his past. Penumbra: Requiem delves deeper into the world of the Tuurngait infection and personalities from the previous two games, Overture and Black Plague. There's even a special price for all three games, available as a pack for just 35USD. This offer is valid only for the Mac and Linux versions.