Kids in the last city holding plus dolls of arbiter master chief, cortana, and others and when u find them all u get an achievement or trophy on ps (sorry ps users i don't play ps much so if I'm wrong about it being a trophy please correct me luv and peace from a Xbox fan) Then another with the USS infinite (sorry if this isn't the name of one of the ships I've been up for the past 28 hours) and again unsure of a name.