User blog comment:Kelis98/BioShock Spelling?/@comment-10023421-20160703230851/@comment-3967731-20160708184136

If you have seen it spelled with only the "B" capitalized then that is the fault of the writer. It has always been meant to be spelled "BioShock," but others have not realized this.

Confusion might come from the box art and/or the title screen in which the capitalized Century Gothic / Futura font makes it impossible to tell. Consider that BioShock is just another entry in the "Shock" series that began with System Shock. With that in mind, the capitalization makes a little more sense even if it is all one word.