▁speed ▁ratings . ▁ ▁Most ▁weapons ▁give ▁off ▁heat ▁when ▁fired , ▁indicated ▁by ▁a ▁he ating ▁gauge . ▁This ▁heat ▁diss ip ates ▁when ▁firing ▁ce ases . ▁If ▁the ▁need le ▁passes ▁the ▁orange ▁and ▁then ▁red ▁zones ▁of ▁the ▁gauge ▁the ▁ship ▁over he ats , ▁and ▁it ▁will ▁be ▁unable ▁to ▁fire ▁until ▁the ▁need le ▁passes ▁back ▁behind ▁the ▁orange ▁zone . ▁This ▁makes ▁upgrad ing ▁the ▁cool ing ▁system ▁essential . ▁With ▁an ▁improved ▁cool ing ▁system , ▁the ▁ship ▁will ▁take ▁longer ▁to ▁over he at , ▁and ▁will ▁cool ▁down ▁faster . ▁Miss iles ▁and ▁bomb s ▁do ▁not ▁generate ▁heat . ▁The ▁rate ▁of ▁fire ▁for ▁miss iles ▁is ▁determined ▁by ▁their ▁upgrade ▁level . ▁Bomb s ▁are ▁the ▁only ▁weapons ▁that ▁have ▁a ▁limit ▁per tain ing ▁to ▁how ▁many ▁can ▁be ▁fired ▁at ▁any ▁given ▁time . ▁Each ▁bomb ▁that ▁is ▁dropped ▁uses ▁up ▁a ▁portion ▁of ▁a ▁slowly ▁re pl en ishing ▁' b omb ▁meter '; ▁the ▁amount ▁used ▁by ▁each ▁bomb ▁decre ases ▁with ▁up gr ades . ▁ ▁Plot ▁In ▁J ets ' n ' G uns , ▁the ▁player ▁starts ▁out ▁as ▁a ▁fre el ancer , ▁contract ed ▁to ▁drive ▁out ▁a ▁gang ▁of ▁crim inals ▁from ▁a ▁sector ▁of ▁space . ▁So on , ▁the ▁player ▁is ▁contact ed ▁by ▁their ▁old ▁command ing ▁officer ▁from ▁a ▁previous ▁war , ▁Col . ▁Tr ou blem an , ▁who ▁is ▁based ▁ab o ard ▁the ▁United