It's a fantasy role-playing game.

DM: You are Percival de Rolo, a human gunslinger . You are the member of the famous group of adventurers. Previously,  They then encountered a very elderly goliath that Grog hadn't seen in quite some time named Shale, who spoke of the scouting crew that had been obliterated by the dragon. They followed Shale as she led them up the mountain, to where the dragon's current lair resides.
DM: As you all find yourselves to rest within the confines, the comfortable confines, of Scanlan's mansion, Percy, I want you to go ahead and make a tinkering check.
Player: That's tinkering is plus four, plus proficiency bonus, plus a d20, if I recall?
DM: It's proficiency bonus, plus your dex for the purposes of fixing this.
Player: Okay, that's even better. That'll do. 20.
DM: 20, okay. It takes you most of the evening. You'll rest up but we'll say for the purposes of this you've only regained two hit dice for the evening's rest, of your spent hit dice.
Player: Okay. So I'm just down two hit dice?
DM: Yeah. Any that you've used, if you used any, you don't recover any but two. Normally you'd recover half of your unused hit dice right now. The gun is fixed, the materials that you were required to use will cost you half as much as the actual weapon is worth.
Player: Lord almighty.
DM: Which, let me look at my list here for that-- It's going to come to roughly 400 gold in materials to repair.
