The games take place in the year 2030, between the stories told in Ghost in the Shell: Stand Alone Complex and Ghost in the Shell: S.A.C. 2nd GIG.
In the year 2030, cybercrime, espionage and terrorism plague a society lost between humanity and technology. As one of the trusted members of the government organization known as Section 9, Major Motoko Kusanagi must uncover the truth behind a mysterious case known only as T.A.R.
Source: Wikipedia, "Ghost in the Shell: Stand Alone Complex (video game)", available under the CC-BY-SA License.