, ▁the ▁colon ists ▁were ▁forced ▁to ▁leave . ▁However , ▁The on ▁is ▁now ▁under ▁attack ▁by ▁the ▁same ▁al ien ▁fleet , ▁but ▁the ▁humans ▁are ▁ready . ▁The ▁player ▁assumes ▁the ▁role ▁of ▁an ▁Al lied ▁League ▁of ▁Cos mic ▁Nations ▁( AL CON ) ▁f ighter ▁pilot ▁in ▁the ▁SW 4 7 5 ▁space ▁f ighter ▁craft ▁to ▁stop ▁the ▁inv aders ▁from ▁taking ▁over ▁The on . ▁ ▁Development ▁ ▁Ar cade ▁version ▁▁ ▁S lap ▁F ights ▁development ▁team ▁had ▁a ▁concept ▁for ▁a ▁game ▁that ▁featured ▁secre ts , ▁while ▁its ▁main ▁appeal ▁to ▁keep ▁players ▁invest ing ▁long ▁play time ▁sessions ▁revol ved ▁around ▁hidden ▁items ▁and ▁the ▁weapon ▁power - up ▁system , ▁as ▁then - To ap lan ▁composer ▁Mas ah iro ▁Y uge ▁stated ▁that ▁the ▁team ' s ▁idea ▁for ▁the ▁game ▁was ▁to ▁add ▁many ▁secre ts ▁as ▁they ▁could ▁like ▁one ▁of ▁the ▁al iens ▁from ▁Space ▁Inv aders , ▁which ▁was ▁added ▁as ▁an ▁hom age ▁to ▁T ait o , ▁with ▁Y uge ▁cit ing ▁his ▁lik ing ▁of ▁titles ▁with ▁hidden ▁secre ts ▁and ▁characters . ▁S lap ▁Fight ▁was ▁also ▁one ▁of ▁the ▁earliest ▁projects ▁To ap lan ▁made ▁use ▁of ▁game ▁design ▁documents , ▁though ▁Y uge ▁claimed ▁that ▁these ▁were ▁added ▁after ▁development ▁as ▁post scripts , ▁since ▁the ▁team ▁" ne eded ▁some ▁written ▁records ". ▁ ▁Y uge ▁stated ▁that ▁the ▁weapon ▁change ▁mechanism ▁was ▁intended ▁to ▁be ▁a ▁strateg ic