Does anyone ever stop to think that "replay" doesn't really apply here? You're essentially supposed to power through the short "story" so you can get to 20 and at the end of such, when appropriately ran, you're possibly all decked out in blue gear and using green guns. Who wouldn't want to play more to see what can actually be done with stronger items. You've experienced 100% of the core of this game in less than 12 hours.