Epic Games is best known for shooters like Unreal Tournament and Gears of War. However, with Fortnite they're venturing outside of that genre and creating an experience that many different types of gamers can enjoy.
In Fortnite, a team of players defends a base against zombie-like creatures. However, that's only one half of the game. When the sun comes up, players scavenge for supplies and decide how to arrange their defenses. It's almost like Gears of Wars' Horde mode mixed with Minecraft.
"I will tell you the game will adhere to my mantra of 'play your way,'" Epic's Cliff Bleszinski told Polygon. "I've been banging that drum on all of our products. There's not just one way to play it, which internally sometimes we struggle with. 'Are we a shooter? An RPG? A building game?' We can be all of that."
Bleszinski notes that the game could have player classes. That should give you an idea of the game's vision: a team of players filling different roles in order to keep their base up and running. The internal debate at Epic over classes probably centers around how fluid these roles should be and how easily players should be able to change between them.
To make the game appeal to an even broader audience, Epic will be including mod support. This pretty much stretches the gameplay possibilities to infinity. Even if Fortnite isn't scratching a particular itch of yours, one of the many player-made mods could do just that.
Fortnite is currently slated as a PC exclusive. It'll arrive sometime in 2013.