The saris(s)a was discussed by various ancient authors and its length is know to have varied over time. The numbers I mentioned are all attested. For more details, see Christopher Matthew “The Length of the Sarissa” Antichthon 46 (January 2012) 79–100 https://doi.org/10.1017/S0066477400000150. The justification for giving different civs different pike lengths is that, while 0 A.D. aims to cover the entire 500–1 BC timeframe, each faction is mostly focussed on a particular point in time; e.g