▁map ▁is ▁available ▁which ▁will ▁show ▁Regin a ' s ▁location , ▁destination , ▁save ▁points , ▁and ▁locked ▁doors . ▁Save ▁points ▁are ▁rooms ▁which ▁will ▁prompt ▁the ▁player ▁to ▁save ▁upon ▁exit ing ▁them . ▁Some ▁doors ▁are ▁locked ▁by ▁a ▁D . D . K . ▁( dig ital ▁disk ▁key ) ▁device . ▁To ▁open ▁these ▁doors , ▁the ▁player ▁will ▁need ▁both ▁a ▁code ▁disc ▁and ▁input ▁disc ▁which ▁can ▁then ▁be ▁used ▁to ▁de ci pher ▁a ▁code ▁and ▁un lock ▁the ▁door . ▁There ▁are ▁also ▁force ▁fields ▁of ▁red ▁be ams ▁throughout ▁the ▁complex ▁which ▁can ▁be ▁activ ated ▁to ▁block ▁access ▁to ▁intr ud ers . ▁ ▁Regin a ' s ▁invent ory ▁may ▁include ▁key ▁items , ▁weapons , ▁am mo , ▁and ▁medical ▁supplies — the ▁latter ▁two ▁of ▁which ▁she ▁can ▁only ▁hold ▁a ▁limited ▁amount . ▁She ▁can ▁also ▁mix ▁certain ▁items ▁in ▁order ▁to ▁upgrade ▁them ▁or ▁make ▁completely ▁new ▁ones , ▁such ▁as ▁an est h etic ▁d arts . ▁These ▁items ▁can ▁be ▁stored ▁in ▁" emer gency ▁boxes ", ▁which ▁need ▁be ▁un locked ▁with ▁special ▁items ▁called ▁" pl ugs " ▁before ▁they ▁are ▁us able . ▁Each ▁emer gency ▁box ▁is ▁color ▁c oded ▁as ▁either ▁red , ▁green , ▁or ▁yellow . ▁Each ▁box ▁can ▁access ▁the ▁contents ▁of ▁any ▁other ▁un locked ▁box ▁of ▁the ▁same ▁color . ▁ ▁The ▁player ▁can ▁move ▁with ▁weapons ▁drawn ▁and ▁use ▁automatic ▁target ing ▁functions