▁the ▁mission ▁rather ▁than ▁leaving ▁it ▁and ▁then ▁back track ing ▁later ▁on . ▁ ▁On ▁successful ▁completion ▁of ▁the ▁mission ▁the ▁player ▁is ▁paid ▁and ▁the ▁money ▁can ▁be ▁used ▁to ▁purchase ▁new ▁Land ers , ▁parts , ▁am mo ▁and ▁the ▁bare ▁necess ities ▁such ▁as ▁fuel ▁and ▁shield ▁re charg es . ▁ ▁If ▁the ▁player ▁performs ▁well ▁or ▁performs ▁a ▁special ▁action ▁in ▁certain ▁miss ions ▁then ▁alternate ▁miss ions ▁are ▁made ▁available . ▁ ▁It ▁is ▁not ▁un common ▁for ▁players ▁to ▁complete ▁the ▁game ▁multiple ▁times ▁and ▁end ▁up ▁finding ▁new ▁miss ions . ▁ ▁There ▁are ▁a ▁total ▁of ▁ 2 9 ▁miss ions ▁it ▁the ▁game ▁( not ▁including ▁the ▁two ▁training ▁miss ions ) ▁but ▁only ▁about ▁ 2 2 ▁are ▁played ▁in ▁a ▁single ▁run . ▁ ▁Control ▁System ▁ ▁Although ▁Land er ▁had ▁an ▁ar cade ▁feel , ▁cont rolling ▁the ▁ship ▁in ▁three ▁axes ▁proved ▁quite ▁difficult ▁to ▁master , ▁often ▁taking ▁days ▁for ▁some ▁to ▁become ▁confident ▁and ▁compet ent . ▁The ▁default ▁control ▁system ▁re lied ▁upon ▁mouse ▁movement ▁to ▁control ▁t ilt ▁and ▁roll , ▁whilst ▁the ▁keyboard ▁controlled ▁the ▁y aw . ▁ ▁Land er ' s ▁input ▁system ▁does ▁have ▁a ▁degree ▁of ▁flex ibility , ▁allowing ▁other ▁input ▁devices ▁such ▁as ▁an ▁analog ue ▁jo yst ick ▁and ▁even ▁allows ▁for ▁the ▁use ▁of ▁an ▁analog ue ▁thro tt le ▁to ▁control ▁the ▁ship ' s ▁thrust , ▁allowing ▁for ▁a ▁much ▁fin er ▁control