Ironsworn is an awesome game! It is semi PbtA, but introduces many new mechanics that help the game to flow smoother. It's designed to be run both with or without a GM, and either solo (one player/no GM) or with a group (GM or No GM). It uses the familiar PbtA "Moves" structure to drive the fiction, but doesn't include Playbooks. Instead, you build your character by assigning bonuses to a number of stats and then choosing three unique Asset cards. Each Asset card modifies some of the core moves or provides you with new options during play.
Another unique element of this game is the Vow. A Vow is essentially a quest that you choose and assign a difficulty rank to, and the game automatically measures your progress against the quest using an innovative progress system (a spin on clocks from Apocalypse World or Blades in the Dark). By using Moves and Vows, the game engine largely drives itself and produces new and exciting stories every time you sit down to play.
The book is beautiful with a realistic and gritty art-style throughout, which matches the game's default low-magic setting perfectly. It clocks in at roughly 270 pages spread across 7 chapters that teach you the mechanics of the game and then provides a bestiary of unique foes you might face in the Ironlands. There's a chapter dedicated to random generators to help make your version of the Ironlands unique, a gazeteer chapter that introduces the settting, and a chapter dedicated to teaching new (or veteran) players how to best make use of Ironsworn's unique mechanics to tell great stories.
The developer is incredibly responsive and communicates with the community frequently through the game's Google Plus community (https://plus.google.com/communities/104501626579912652597)
And if all that didn't sway you, it's free!