So it's a trilogy after all.
When the Penumbra series was first announced, Overture was to be the first of three games, but with the arrival of Black Plague came word that the series had been reduced to two games. Now, however, a third part is coming anyway, as Paradox Interactive announced that Penumbra: Requiem will be released this summer.
Requiem is called an "expansion" rather than a full-fledged sequel, tying up loose ends even as the storyline "delves deeper into the world of the Tuurngait infection and personalities from the previous two games". Once again cast in the role of Philip, players will encounter long lost friends who may or may not be trustworthy, and "telling what is real and what is not will be even harder and not always trusting your senses will be essential in order to survive."
Unlike the earlier titles in the horror series, Requiem won't be available on store shelves, or even widely available online, as the game will be offered exclusively through the GamersGate download portal, beginning in June 2008.