I noticed something Steven Moffat did well: opposing each of his various monsters required a different set of techniques.
I had recently played a bunch of Pathfinder, in which too many monsters are little more than differently decorated piles of hit points. These foes may have one or two special abilities that help them attack. But those abilities very seldom change the strategies and tactics clever heroes would use to oppose or fight them.
So I improved my diceless, two-person RPG, Narrative Adventures Made Easy. I revised the NAME monsters. They now are more distinct about how to best oppose them. They also each have their own type of flavorful treasure.
If you have time, I would love to hear constructive criticism at this forum discussion. Do the monsters seem like interesting creatures? Would role-playing the hero or heroine opposing them be interesting and fun?
That monster revision also led to a much smaller editing of the intelligent races.
This time the motivation was to make NAME as kid-friendly as possible. In my experience, lthough kids enjoy being creative they also enjoy becoming "experts" at learning a certain level of rules detail. I tried to reserve fun creativity for people playing the game, while providing fun expertise in rules clarity to minimize PC/GM arguments and help the PC make successful plans.
I made a lot of descriptive "flavor text" blend with what I named traits: carefully worded examples of dozens of exceptions to the game mechanics.
As one example, instead of merely saying that sunlight turns Barrowers to stone, there is now a trait named Defeated by Sunlight that specifies this takes only one turn, requires direct sunlight, and counts as what the game mechanics call "defeating" a creature.As before, constructive criticism is appreciated at this other forum discussion.
But I say nothing about purely narrative issues. What noise do Barrowers make as they turn to stone? Do they thrash about, or freeze in place? When do they drop the stuff they hold, and when does the hero lose the chance to loot the creature of its weapon as that becomes part of a stone statue?