I've been watching the development of some new (and not so new) roleplaying ideas by several people.
There seems to be a common thread in many people's designs where the heroes develop by gaining new abilities and improving those abilities, actually this has been a common thing in pretty much evey roleplaying game except for those designed as one-shots or those that are going out of their way to push the envelope in some way.
What's been more interesting recently is the idea of abilities as a way to manipulate the story's narrative, rather than abilities as a way to manipulate the game world. As a character improves, they gain new ways to manipulate the narrative, or ways to manipulate the narrative in a more significant manner. Maybe this has been a part of the rpg scene since the beginning, maybe there's been a drift away from it, maybe not... Curiously, the "storyteller" system drifts away from the idea and toward a set of mechanisms where the characters manipulate the world through their abilities rather than the players manipulating the narrative through their characters. Mage came the closest to the purity of my thoughts, because the game world is utterly fluid... belief controls everything, and belief requires conscious thought on the part of the characters, and through them the players are capable of derailing any story and therefore must be the centre of the narrative.
The spheres in Mage are simply flavours of how the narrative can be manipulated and to what extent this occurs in the world. If everything else were stripped away about the game... attributes, skills, merits, flaws... everything... it would still work. Most of the other games in the series wouldn't, they need the grounding in the world and their character abilities are all about navigating that world.
That kind of brings me back to some other ideas, ideas that needed a bit of context before they made a lot of sense. It's a bit of a paradigm shift, and it might be a bit radical for some readers, while some people might have been thinking this way for a while.
Let's look at the traditional D&D classes as all being different types of mystic. Mage the Ascension basically does this with different types of characters using magic to achieve superhuman feats of different types, but at the basic level that's what D&D does too. It tracks the ascension of characters from the every day levels of their origins to the potential levels of demigods and immortals. A warrior gains the ability to deal damage far beyond the mortals around them, they basically become avatars of war and death. A rogue gains an affinity with the shadows, the ability to move anywhere and everywhere, and becomes ever closer to the primordial trickster. A mage is the most blatant mystic, exploiting loopholes in reality to create effects that mundane mortals simply cannot understand. A cleric follows those who have walked the path of ascension previously, or those primorial entities who need disciples in the mundane world to become anchored against oblivion. Every class focuses on it's own way to manipulate the world and manipulate the narrative, the warrior excels when the narrative shifts to combat, the rogue excels when the narrative requires deception, the mage excels when the narrative shifts to the arcane, and the cleric excels when the narrative deals with outside forces from beyond reality.
The same idea can basically be applied to any set of game mechanisms. What do you want the stories told through this game to be about? What sorts of things do you want experienced veterans to find easier? What sorts of things should remain a challenge? Do you want the characters/avatars in the game world to expand their options for interacting with the story (in old school games we might call is multi-classing, in more moden games we might call it a skill-based rather than class-based system)?
Even the "Powered by the Apocalypse" games, this idea seems to hold true, different types of character have different narrative-manipulations that they are attuned to. As you improve a character you can buy new methods of narrative manipulation, or you can boost your attributes which give you a better chance of manipulating certain types of narrative conditions.
I'm sure that there is more to discuss in this field, but that's where I'll stop for the moment.