I've been thinking about doing Amber using either 4E or the new (not yet published) 13th Age rules system. 13th Age is a new game which is advertised as being essentially a streamlined 3E/4E blend. (I'm not super familiar with either 3E or 4E to really know how to compare them. I mostly play OD&D but have enjoyed the few 4E games I've played in. 3E seems to have too many numbers.) Someone at my local game store has run a couple of 13th Age demos, which is what inspired me to think about 4E again.
A couple of thoughts about what I might try:
(1) I would be tempted to create a list of simple powers (at-will, encounter, daily) for each of Pattern and Logrus and Trump and so on.
* For example, "Walking the Pattern" could be a daily ability while "Shadow Walking" might be an encouter ability and "Pattern Defense" might be at-will.
* "Create Trump" could be daily, "Use Trump" at-will.
(2) I was thinking that I would define the "average" Amberite as having a 10 attribute, so that shadow creatures would be below this. Doing it this way would allow me to retain the basic point-buy method of stat generation.
(3) Basic shadow creatures would use the "mook" rules and get mowed down. This tends to separate "real" folks from shadow folks. Characters wouldn't be invincible, but would be equal to a large number of shadow creatures.
(3) I was thinking of essentially eliminating character advancement, at least in a traditional sense. Have players create characters at perhaps 4th level and then mostly stay there. Enough experience could translate to slowly adding extra abilities as per Amber Diceless.
(4) Part of what I like about 13th Age is that they place a decent emphasis on storytelling and not just combat. In character generation you need to establish (i) one unique thing about your character, (ii) several good or bad relationships with some of the movers-and-shakers of the world, and (iii) some simple background skills. The relationship part certainly seems to fit an Amber setting, where someone might be tied to various Elders. I assume that this concept could be imported to any 4E setting.
Anyone familiar enough with 4E (or 13th Age) to lend some thoughts or ideas about this?