So, re this FATE conversion thing:
Separate skills for "Athletics" and "Somatics", or "Impersonation" and "Deception", or any number of other closely related skills, are unnecessary. You can trim it down by using something I'm going to call a familiarity penalty.
Basically, if you're using a skill for something just outside its purview - for example, if you're trying to use a "Deception" skill to impersonate - you can do it, but at a penalty to the roll. If you continue to use "Deception" to impersonate, the penalty will shrink and eventually disappear.
Similarly, if you're trying to freerun across rooftops on Titan, and you have "Freerunning" but you hail from Mars, attempting to use the skill will incur a familiarity penalty for the different amount of gravity. Once you practice enough on Titan, the familiarity penalty will disappear.
This requires some GM eyeballing but it is much closer to the spirit of FATE/narrativist systems in general than ridiculously long skill lists are.
(I originally borrowed this notion from Chuubo's Marvelous Wish-Granting Engine but GURPS has it too, sort of.)