Complex sentence: Once the campaign is completed, the player is given a final rank for the overall campaign, and by achieving S-Rank or A-Rank, the player gets the opportunity to purchase more unlockable elements from Battle Maps.
Split into simpler sentences: Once the campaign is completed, the player is given an overall rank for the overall campaign. By achieving S-Rank or A-Rank, the player gets the opportunity to purchase more unlockable elements from Battle Maps.