Here are the sorted bricks. There are a lot, about twice as many as a typical $15 set with minifigs, and they are mostly bigger bricks suitable for making good-sized terrain features:
The terrain building went really well. I quickly ended up with many good terrain segments, capable of setting up a wide variety of scenes. I wouldn't want to try to run a whole campaign with just this box, but it gives a solid foundation to add to. Here are some example setups, with a grid cloth and minifig from my collection:
Here is everything I built all together:
I made the outdoor terrain first, a grassy hill and a rocky cliff face. There are enough slopes in the set to make a very nice natural effect.
Next came a giant stone skull, surrounded by magical flames:
Then the creatures. This set contains mainly bricks, with no plates or advanced elements aside from a few headlight bricks, so they are not up to modern standards of brick-built creatures, but they would work as animated statues.
A torii gate:
And then the leftovers got mashed into a decorated facade:
Not pictured individually are a set of tables and chairs, a decorated gray pillar, two more animated statues, and the other red-brick water fountain.
I ended up with a lot of terrain for $14 and a couple hours of enjoyable building. My initial guess was correct, this box of bricks is a great way to build good Lego RPG terrain.