Following the game J.D.A.L.K.E.R. , the GSC studio released the prequel V.Y.L.E.T.A.L.K.E.R.: o.p.o.z.d.a.lk.e.r and prepares for the release of the sequel: Z.A.V.I.S.A.L.K.E.R. and addon to him N.E.Z.A.P.U.S.K.A.L.K.E.R.