In FUBAR (and by extension, Walkabout), the skeleton consists of the "otherkind" mechanism where players roll or draw a series of random outcomes then allocate their results to different categories before applying the result back into the story. That's clever, it's not mine (and credit has to go to Vincent Baker for that one), and a lot of people love that about the games. Another bone is the pool of tokens that represent the challenges to be overcome as the characters work their way to the climax...this one is mine, and it also stays.
The bits that cause the dilemma are the "forced scene and act structure" of the game, and the flowing economy of trait cards. Both of these are specifically linked to one another, and while they connect to the other parts of the game via other flexible rules (muscles in the analogy) they can be modified.
One of the problems with specific designation of acts and scenes is that it can be hard to determine when one ends and another starts...this applies to the transition between scenes, as well as the transition between acts. I've found that making a definitive break point between scenes can be jarring...and more often than not, a long period goes by during the course of play and I look at the traits built up by players, I see that I've neglected certain traits that have completely lost their relevance because I've forgotten to specifically declare an end to a scene or an act...sometimes I miss it completely, and a player specifically says to me "I got injured a while back, does it still affect me?"
The game structure is fairly minimalist in its design, and little things like this shouldn't be happening. So there is obviously something wrong.
I'm thinking that the best way to fix it is to take a leaf from the game "Agon" by John Harper. This game has influenced a few of my designs over the years, it's got a lot of clever tricks in it. Specifically, in this situation I'm looking at the idea of taking breaks during the course of the story.
The players decide when a break is to be taken, and when they do this they overcome some of their penalties...but so do their adversaries. It's something I use in "Tooth and Claw", and it makes an appearance in "Voidstone Chronicles".
With this in mind, I'm going to streamline the traits in FUBAR/Walkabout. I stead of allocating them values according to story duration (situational lasts a scene, short term lasts an act, long term lasts the story, permanent is self explanatory), I'll now allocate traits a bit differently and reduce their number of levels. Situational traits will be eliminated as a concept. Short term traits last until the players decide to take a rest (or can be countered by opponents/action sacrifices). Long term traits last the rest of the story. Permanent traits are still self explanatory.
This puts the control of traits into the hands of the players. They decide when they've accumulated too many penalties, and need to weigh up a decision about whether it is worth losing their beneficial traits.
This also means that instead of a rigid act structure, the story now follows a more natural progression.
Like everything, this is a work in progress. It's a fundamental shift in the underlying mechanisms of the game, and theoretically it makes sense...the only way to know if it works is to see it in play.