 The single @-@ player mode consists of a sequence of missions set as an overarching story . Each mission requires the completion of certain objectives to progress to the next mission . The objectives are usually the elimination of enemies or a certain structure , but several of them test the player 's eye – hand coordination or require the player to rescue and protect certain units . Players control their characters from a default third person perspective ; a first person view is optional . Each race has its own offensive style , and a special mode of fast movement . Killing a creature releases a power @-@ up , which heals or awards weapons to its collector . 
