There are a bunch of AAA-ish? RPGs and strategies on Unity, like Pillars of Eternity, Pathfinder, Endless Legend, Endless Space. They may not have the player numbers of Heartstone but they are basically what top notch equivalents like like Baldurs Gate or Civ are, and more.

In my experience Pathfinder for example suffers from poor perf compared to e.g. Tyranny, but Endless Legend doesn't compared to recent AoW or whatever non-unity game equivalent.