about Fortnite game modes

Currently, Fortnite is distributed as two different games, though each game uses the same engine and has similar graphics, art assets, and game mechanics.

Fortnite: Save the World is designed as player-versus-environment game, featuring four players cooperating towards a common objective on various missions. The game is set after a fluke storm appears across Earth, causing 98% of the population to disappear and the survivors to be attacked by zombie-like "husks". The players take the role of commanders of home base shelters, collecting resources, saving survivors, and defending equipment that help to either collect data on the storm or to push back the storm. From missions, players are awarded a number of in-game items, which include hero characters, weapon and trap schematics, and survivors, all which can be leveled up through gained experience to improve their attributes.
Fortnite Battle Royale is a player-versus-player battle royale game for up to 100 players, playing alone or in squads of two or four. Players airdrop from a "Battle Bus" that crosses the game's map without any weapons. When they land, they must scavenge for weapons, items, and resources, avoiding being killed while attacking other players. Over the course of a round, the safe area of the map shrinks down in size due to an incoming storm; players outside that safe area take damage and can be killed. This forces remaining players into tighter spaces and encourages player encounters. The last player or squad alive is the winner.
Both game modes give the ability to player to use a pickax to knock down existing structures on the map to collect basic resources (wood, brick, and steel), from then which they can build pieces of fortification, such as walls, floors, and stairs. Such fortification pieces can be edited to include other features such as windows or doors. The materials used have different durability properties and can be updated to stronger variants using more materials of the same type. Within "Save the World" this enables players to create defensive fortifications around an objective or trap-filled tunnels to lure husks through. In "Battle Royale", this provides the means to quickly traverse the map, protect oneself from enemy fire, or to delay an advancing foe.

Both game modes are set to be free-to-play titles, though presently, "Save the World" is in early access and requires purchase to play. Both games are monetized through the use of V-Bucks, in-game currency that can also be earned only through "Save the World". V-bucks in "Save the World" can be used to buy pinatas shaped like llamas to gain a random selection of items. In "Battle Royale", V-bucks can be used to buy cosmetic items like character models or the like, or can also be used to purchase the game's Battle Pass, a tiered progression of customization rewards for gaining experience and completing certain objectives during the course of a "Battle Royale" season.