Plenty of publishers are walling off certain game content behind an "online pass," a one-use code that's included free with a retail copy but likely burnt up in that used disc you just bought for a lot less. In most cases, it covers something like online multiplayer. Not Rage.
Speaking to Eurogamer, Tim Willits, the id Software creative director, said that access to the game's underground will be restricted to those who get their copy new at retail. "You've played Rage five times. Have you found any sewer hatches?" Willits asked his interviewer. "If you bought the game new, that would be open for you. "
He added:
You still have to download it, but you don't have to pay for it. Those hatches are all over. Most people never find them. But as soon as you do, you're like, oh. And then you start to look for it. That's our first-time buyer incentive.
Willits figures this is less obnoxious than other Online Pass mechanisms because, in those instances, people know what they're missing. Not with Rage! "Some people will buy Rage, download that, and still never set foot in those things. They just won't. I think that's fair. It's cool," he said.
The sewer-system content is "outside the main path" of the game, so therefore its absence — whether one is entitled to it or not, I suppose — won't diminish the story.
No word if this sewer access will later be made available through a separate DLC unlock.
Tim Willits: Building Rage And Never Selling Out - Interview [Eurogamer]