theres a few things that absolutely must stay in the game
1.the vaultboy pictures (mr. pipboy?)
2.the leather jacket
3.the chance to get extra professions (be a boxer, porn actor, martial artist, etc. along with new ones of course)
4. the S.P.E.C.I.A.L. system, and the skill system as well
as for slavery and whores i think they should stay too, this is suposed to be a world you dont wanna live in
in can live without a car but it would make it much cooler
also all the pop culture references... the game wouldnt be the same without them.. its what gives it the special kind of humor that made me love it