Fallout 3 uses the S.P.E.C.I.A.L. system (strength, perception, endurance, charisma, intelligence, agility, luck...I believe), which came from the first two Fallouts. Instead of increasing your skills by performing actions, you earn XP from killing, questing, or using your repair/hack/lockpick skills. When you level up, you get to put points into your skills. You get perks every level that grant you skills or unique abilities. Every few levels you get to boost one of your SPECIAL stats. It flowed well and let you play a character type you actually wanted. Although, by the end, if you knew what you were doing you could be proficient in almost everything.