Survival

This is the skill to survive in the post nuclear wasteland. This skill encompasses the knowledge on how to find potable water, how to erect a tent, which of the meager plants there are edible, how to find the right way based on sun, moon and stars, how to make fire and all that.
Bonuses and handicaps depend on the specific task (starting a fire after it rained is more difficult than during a drought. Since this skill is very complex, we'll leave it at that one example.)

The starting value is: P + A + E + I