Life Hacks/Mods Guide/Adjust Skills
Skills in this story are far too numerous to list. Basically anything that you can learn is a skill. Some of them are just accumulations of knowledge while others represent the ability to preform an action. Like in life some skills cannot be learned without meeting a prerequisite attribute level, trait (or lack of certain traits), or world condition. A blind man would have extreme difficulty learning to paint a picture. If you have an IQ of 40 you are NOT going to be learning how to perform brain surgery. You are not going to learn to perform contortionism without either having extremely high flexibility, being double-jointed (which is just more elastic tendons), or preferably both. You can't learn a dead language unless there is someone alive that knows that language that could have taught you. You can't practice winged flight until someone invents a functional ornithopter wingsuit (or you grow wings). You can't learn to cast a fireball if there is no magic. You see where this is going.
Trying to list every possible skill and its prerequisites would be an exercise in futility, so I will not be doing so.