Well, I failed on Day 3 for a variety of reasons. So, rather than continue the numbering, I've begun the letters to indicate all work done after November 2012.
But the Axion system has still been percolating in my head, alongside other RPG needs.
With the latest Fate and Gumshoe entrants into the RPG arena, I'm quite happy to leave the 'story engine' RPGs to them. I'm still firmly looking at the 'physics engine' emulation arena, though comic book physics does sometimes give in to rubbery science.
Hero / Fuzion and DC Heroes are the ones that really seem to have given this action movie / comic book physics engine some thought, with the exponential progression of values. However, DC Heroes tied these to all attributes, some of which didn't necessarily apply strongly to real world measures and raised questions like: "Is Braniac 5 as smart as Superman is Strong?" and so on.
A further idea arises: should I follow the "every 5 points doubles the game value" of Hero, or the "every 1 point doubles the game value" of DC Heroes? I know that Mutants and Masterminds made some clever re-use of the DC Heroes AP tricks.