Developer Fictiorama Studios and publisher Daedalic Entertainment now offer a prequel game for everyone who owns Dead Synchronicity: Tomorrow Comes Today on Steam. They say this is a thank you to fans, noting that it differs from the main game: "It's a delightfully old-school parser-based graphic adventure, designed to give players the chance to learn more about the world of Dead Synchronicity." Here's more from the announcement:

Summer is here, it’s hot and we somehow missed to inform you that we made you a gift.
For those among you already owning Dead Synchronicity or who are going to purchase it, there is the prequel text-adventure Dead Synchronicity: The Longest Night for free.

You once again will assume the role of Michael and learn what happened, before he lapsed into a coma.
Dead Synchronicity: The Longest Night is a text based graphic adventure with a classical text interface.

So basically this means that here the prequel of Dead Synchronicity: Tomorrow Comes Today is told in an old school adventure style, to give you the chance to learn a little bit more about the background of the story.