From the Kickstarter Blurb:
Dungeon World is a fantasy roleplaying game about exploring dungeons, fighting monsters and looting treasure. In Dungeon World you and your friends take up the role of classic character classes and undertake exciting adventures together. Through your triumphs and travails the world changes around you.
The Dungeon World rules are simple and elegant. They exist to help you create unpredictable adventures and fluid action—to move from battles to exploration to moments of magic and mystery with ease. Dungeon World's rules all tell you when to use them: every rule comes into effect just when it's needed and stays out of the way the rest of the time.
Dungeon World emerged from our love of two things—modern game design and old-school RPG action. We wanted to create a game with the wide-eyed excitement and wonder of your first time playing a fantasy RPG and rules that draw on a long history of innovation and creativity. The best of both worlds!