Released over seven years ago, City of Heroes put a stake in the ground for superhero MMOs -- and continues to be a successful title for its publisher, NCsoft. Recently, Gamasutra had a chance to speak with lead systems designer Matt Miller and lead producer Nate Birkholz. "Superheroes probably shouldn't have been the next type of MMO," Miller says of the situation on the ground at the time of the game's release in 2004, when fantasy and sci-fi had already been established as sub-genres -- "It was kind of weird." However, he says, "I was happy that we had that space that we did, and that risk that we did, because it really gave players who liked MMOs a very unique world to play in." Miller has been working on the game for "almost eight years", having started prior to its launch, and continues to shepherd its development -- through 20 "issues", or free content updates for its players, the latest of which was released in April. Of his tenure on the team, Miller joked to Gamasutra, "I'm responsible for typing up the original XP tables, so..." "So, you're to blame," Birkholz quipped. "Yes. I'm to blame. I fixed it every time, too. I've revised them like four to five times over the past seven years," Miller replied. Running the same game for so long, Miller says, "I personally have learned a bunch." He " went into this thing with the risk/reward mentality. So, the harder something is, the better reward I need to get. But, you know, that was me eight years ago. "It does need to be difficult. It does need to be hard. But it really needs to be a time reward mentality. How much time is invested, of yours, should determine the reward you get out of it. The more time, the better reward, right? Because your time is valuable." Keeping an audience engaged over such a long period of time is obviously a challenge. How has City of Heroes done it? "When it comes to like the secret sauce as to how we've been so successful for over seven years now, I think it's because we've never stopped innovating and we've never stopped developing," Miller says. "We never once said, 'You know, okay, well this is the last major thing we're going to add to the game, and after this, we'll just go into maintenance mode.'" The most recent update, Incarnate, was a response to the high-level endgames in other MMOs -- something the game lacked at its outset, thanks to the team's more casual approach to the genre. "When we first launched City of Heroes, the concept of an end game was an EverQuest 12-hour planar raid, right? That was not going to be our game." The members of the team "liked MMOs, but we weren't hardcore MMO players," says Miller. "I wanted to make a MMO that was accessible to me and my friends, where we could have a bunch of stuff to do while we were leveling up that was akin to the things that we were seeing in other games." The new endgame, however, fills "a perceived need. It was something lacking in our current content." However, he says, "I didn't really want to be a me-too onto the competition. I wanted to make our game better. I wanted to listen to our players. What were our players asking for?" Like any good MMO developer, Miller turned to the forums, not to the competition. "It wasn't really in response to any other game out there... I think we have maintained our lead over all the [superhero MMO] competition because we do listen to our players." Like Blizzard, Miller has found that players these days demolish the team's content -- as with Incarnate -- faster than anticipated. Says Birkholz, though, "We've got an awful lot of content in the game, so you can always find something to do and someone to do it with." Miller agrees. "We have over seven years of content development in this title, right? That is something that brand new competition cannot say, and I dare them to match... The game is built around breadth and having things to do with alts that you haven't done with your main character." However, he admits, "some of the older content does become irrelevant. We try and work that into the schedules... If we invalidate... missions, how much work is it going to be, you know, change them or fix them or update them? For [expansion pack] Going Rogue, I actually spent a couple weekends... I came in myself since I knew that content the best, and went in and altered the missions so they fit the storyline better." Says Birkholz, "We want to be a game that's constantly growing, and the more time we spend re-doing old content is growth in a maybe more spiritual sense."