Omikron: The Nomad Soul is being given away by publisher Square Enix from today through till January 22 in the memory of David Bowie, who appeared in the game.
— Square Enix (@SquareEnix) January 15, 2016
Omikron: The Nomad Soul is the first game made by Quantic Dream- of Heavy Rain and Beyond: Two Souls fame. It was released in 1999 and Bowie performed songs from his album Hours within it; some of which were written with the game in mind. He also contributes vocals for two in-game characters* and maybe had some input into direction of the story.
Omikron is a mesh of various different game genres; borrowing elements from first-person shooters, fighting games, adventure games and puzzlers. The story involves hunting down a serial killer and you can switch bodies also.
* Specifically, he played Boz, a revolutionary wanted by the government, and a singer who performs at illegal concerts.