A Fantasy Heartbreaker's basic, imaginative content is "fantasy" using gaming, specifically D&D, as the inspirational text. What's D&D Fantasy? Well, it's about seting up a character starting-point with a strong random component as well as a strong strategy component, having encounters, surviving them (or not), and improving. What characters do is travel, team up, bicker a bit, walk a tightrope between cooperating and exploiting one another, suss out threats (risk assessment is a big deal), and fight with unavoidable or especially rewarding ones. Some giveaway details: gotta have elves and dwarves, gotta have underground complexes, gotta have teams of adventurers, gotta have array of tactical possibilites for combat (armor/weapons), gotta have similar array of spells, gotta ramp up the range and scope of both arrays with "experience," and gotta have a chock-full smorgasbord of threats.
(I want to emphasize that terms like "Tolkien fantasy," "traditional fantasy," and "high fantasy" are often used to refer to D&D fantasy, all of which I think are highly inaccurate and obfuscating.)