I'm still maintaining that a progression system of unlock is not a valid replacement for engaging gameplay and story. if you feel the need to force your customers to play your game through such tactics by waving a carrot further down the road then you are doing something wrong. The game should be able to stand on it's own because it is enjoyable, and having your playerbase staying only because they feel ''invested'' after going through the heavens forsaken progression system is not a good thing at all. Make a fun game and people will play it, make a half decent game and put on a progression unlock system and people won't play it once they realize that they are actually not having fun, they are just being distracted.