Okay so most series have a point where they stop putting semi-honest numbers in their name and start putting subtitle words that begin with RE- (Resurrection, Retribution, Redemption, Return, Reloaded, Revolutions, Recurring, Repetitive, Recon, Reach, etc.) , like the series is now an email conversation or something. Halo, excluding the absolute worst titles but including Halo 4, has remained faithful to the number-rule of sequel nomenclature. But how long will this keep up? Almost everyone stops at 3, Call of Duty stopped at 4, Fast and Furious stopped at 1 but paradoxically went back to it for 5... Edit: If you think they'll keep using numbers, when do you think they'll start using roman numerals?