Stonetop is from an excellent family of narrative-focused games called PbtA, or Powered by the Apocalypse. They’re much less tactical compared to something like D&D 5E or Pathfinder, and more focused on ensuring interesting narrative outcomes.
The core mechanic is this: When the characters try to accomplish something risky, they roll 2d6 and add one of their attributes (Strength, Dexterity, Constitution, Wisdom Intelligence or Charisma, which range between -1 and +3). If they get a 10 or more on the dice, they get a Strong Hit, and achieve their objective! On a 7-9, they get a Weak Hit. A weak hit will let them partially succeed or succeed with a cost. 6 or less means they Miss. They fail, and the situation turns against them — sometimes very badly indeed, depending on the situation.
These rolls are always part of Moves. Moves are actions that characters take when ‘triggers’ in the narrative occur — like Clash, which is triggered when a character fights in melee combat with a foe, or Seek Insight, when a character studies their surroundings and tries to learn something about the situation at hand.
When I break down the game mechanics behind the story, I will mention the names of moves that the characters are using, and tell you how those moves are being resolved. Sometimes, I’ll share the exact text of the move, but often I’ll just give the jist. In the course of this, you’ll probably learn a bit about how Stonetop is played.