Purchased all skills in all categories.
Skills can be purchased as you progress through the game as you gain experience and level up. You buy these skills at the campsites. There are 3 tiers of skills, and you unlock them as you purchase the ones in the tier you have. There are a total of 24 skill to obtain and you must be at the skill level Specialist. There are only 3 categories: Survivor, Hunter, and Brawler.