Just like many sandbox style games you have the main missions and the side missions, the main differences being are the length of the missions and difficulty. (darkstation.com)
They all take series which operated in either limited open or linear worlds and turned them into sandbox style games. (blackgirlgaming.com)
Dead Rising is everyone's favorite zombie slaying sandbox style game and with the recent release of Off The Record the game series can only continue to grow right? (wccftech.com)