Before BioShock Ken Levine worked on the System Shock series and Steam is running a 30% off sale for System Shock 2 until May 17th.
You can pick up Irrational's classic for just $6.99 at the moment. The original System Shock is unfortunately not on Steam but its sequel is still a good means of discovering the foundations for what would lead to BioShock Infinite and bears a 92/100 rating on Metacritic.
System Shock 2 was released on PC in 1999 and was published by EA. The action RPG-horror title includes both co-op and single player modes and in true Irrational fashion tells its backstory through audio logs the game's protagonist picks up as the player progresses. As the game is a horror ghostly apparitions also divulge details of the plot.
Players can choose to be Marines, Navy officers or OSA agents and each class comes with its own unique benefits. The game is set in 2114, 42 years after the original System Shock. A Dreamcast port of the title was planned but never materialised.
We've included System Shock 2 in our list of the Top 25 survival horror games at number seven.