Big changes are coming to the PC MMO Guild Wars 2.

Today at PAX Prime, developer ArenaNet announced that the Guild Wars II base game is available to play for free beginning now, August 29. The business model transition comes three years after the game was originally released in August 2012. In that time, the game has seen more than 40 free content updates and sold in excess of 5 million units.

Although the Guild Wars 2 base game is free, the upcoming expansion, Heart of Thorns–due October 23–will be paid. The main decision behind making Guild Wars 2 free is to encourage people to jump into the game with the hope that they will eventually upgrade to Heart of Thorns.

“If people are expecting we’re going to go in and heavily monetize free players now, that’s not what this is about,” ArenaNet president Mike O’Brien told GameSpot. “This is about making the base game available for everyone to try because we believe that when people love Guild Wars 2 they’re going to buy Heart of Thorns. We’re not changing the way people purchase cosmetic items or adding a bunch of new items in the store. Guild Wars 2 will remain the same game it always has been.”

ArenaNet also today announced that raids are finally coming to Guild Wars 2. These will be 10-player instanced challenges where players must work together to defeat powerful, endgame bosses. The game’s first raid will be released across three parts–wings, as they’re called–“shortly” after Heart of Thorns arrives in October.

“Once we activate the first raid in Guild Wars 2: Heart of Thorns, players will quickly discover that our raids are not waiting to have fun nor about endless gear grind–there are no attunements to complete before you raid, and they won’t become irrelevant or even drastically easier because of a new tier of gear or a level cap raise,” Guild Wars 2 game director Colin Johanson said.

“If people are expecting we’re going to go in and heavily monetize free players now, that’s not what this is about” – O’Brien

“There will be no wasteland of forgettable raids left behind as we continue to expand the system. Once players complete a raid and beat the final boss, it will be a meaningful event that will linger for them, their guild, their friends, and any player who learns that they’ve beat it.”

ArenaNet also claims that its raids will vary from those available now in other MMOs.

“[Our] take on raids will be distinctly Guild Wars 2, factoring in the action-based combat system in the game to replace UI-gazing with active strategies such as weapon and ability changes on the fly in combat, skill combos, dodge rolling, positioning for attacks, and the ability to heal for every class,” Johanson said. “They don’t rely on the conventional tank, healer, and damage dealer ‘trinity’ to take on challenges. Instead, all players in a group will need to step up and support, control, and do damage in encounters in order for the group to succeed.”

To go deeper into Guild Wars 2’s business model change, we spoke with ArenaNet president Mike O’Brien. He talks about why ArenaNet made the change, what impact it may have, bonuses for existing players, and more. Take a look at the full interview below.

When did you decide you wanted to make the base game free, and what were the driving factors for that decision?

Mike O’Brien: We are getting ready to launch our first expansion Heart of Thorns later this year, and so we’re at a time when we have a lot of new players coming into the game. And it’s a great time for new players to come into the game. This is a time when we’re about to launch an expansion that has a lot of new endgame content. It has the new Mastery system that brings character progression beyond level 80. It has awesome group content such as reworked Fractals, which are our five-man dungeons. And it has raids. With all of this new endgame content coming we thought this is the right time to get new players into the game–this is the ideal time for them to create their characters and get them ready for the launch of Heart of Thorns. That’s what made this the perfect time for this transition.

How do you anticipate fans will react to this change, both in-game and out?

I think for fans there are obvious great things about expanding the community and getting more and more people in Guild Wars 2. But fans will be and should be–they have a right to be–protective of the community that they’ve built. Guild Wars 2 is famous for having the friendliest community in online gaming, and we owe it to fans to protect that. We’ve put a lot of effort into making sure to get the details right here. The details involve ensuring that we can protect our existing community while still making it easy for fans to introduce their friends to the game.

Will existing players who bought the base game be getting any bonuses?

Earlier this year, right after we introduced our pre-purchase program for Heart of Thorns, we gave a free character slot to all existing players. This week we also have a special anniversary gift for all of our existing players [following up on this].

Is anything in the base game changing, either in terms of what you can access or new things for you to buy with real-world money?

There are some tweaks to what free accounts can access. First, free accounts start with less storage–fewer character slots and bag slots–than paid accounts, but they still get the full complement of storage as soon as they buy the game. Second, free accounts have some subtle restrictions to chat and economy interactions, specifically so they can’t be used to abuse the game with botting and spamming. So, for example, free accounts can whisper just like paid accounts can, but they can only start one new whisper conversation every 30 seconds. Third, free accounts have to play the game normally before getting to some areas where they could otherwise be used to disrupt the game for other players. In particular, they should play to level 60 before joining WvW. We’ve spent a lot of time tweaking these restrictions to get the right balance where free accounts are getting the authentic Guild Wars 2 experience but can’t be used to abuse the game or other players.

Guild Wars 2 was not originally designed as a free experience; what kinds of challenges did you face transitioning the game, and what are the big opportunities now that it’s going free?

If you notice, we’re not using the words free-to-play with Guild Wars 2. We believe in buy-to-play, and we know that when people describe something as free-to-play that comes with expectations. If people are expecting that’s what we’re doing with the game, if people are expecting we’re going to go in and heavily monetize free players now, that’s not what this is about. This is about making the base game available for everyone to try because we believe that when people love Guild Wars 2 they’re going to buy Heart of Thorns. We’re not changing the way people purchase cosmetic items or adding a bunch of new items in the store. Guild Wars 2 will remain the same game it always has been.

You’re not taking the traditional free-to-play approach that some other MMOs have; why?

We’ve been championing buy-to-play for a decade ever since the original Guild Wars. We think it’s a great business model for MMOs. We think it’s good for players; we think it’s good for developers. With Guild Wars 2 we’ve always tried to be mindful of our in-game shop, the gem store, and what we sell in the game. We’ve always tried to make sure that Guild Wars 2 is a game where you come into it and you’ve got the whole game. There’s nothing tricky going on. We are continuing that as we make this transition. We think this is fantastic value and that players are truly getting the authentic Guild Wars 2 experience for free. Again, we can do this because we believe when players come into the game they’ll love it and consider upgrading to our expansion, Heart of Thorns.

On a wider, industry level, do you think MMOs have to be free to be successful? There is one example out there of an MMO that continues to be subscription-based with millions of subscribers…

I don’t think MMOs have to be any one thing to be successful. We have a great example of an MMO that’s buy-to-play and has been very successful. We’ve sold 5 million copies of Guild Wars 2 as a buy-to-play game and it continues to grow. We have a lot of new players coming in. Looking back, we’ve shipped 40 major content updates since launch. Now we’re getting ready to launch our first expansion, and we’ll be continuing content updates beyond that. We’re making this transition to free because it’s the right thing for our game, because it allows us to keep our buy-to-play business model and keep it very simple and clear as we launch an expansion. There’s only one thing to buy. This isn’t something we have to do; it’s something we’re choosing to do.

Do you ever think about the possibility of [World of Warcraft] becoming free some day and how that could impact the level of differentiation between your game and theirs?

We’re inspired by many different things in our industry, but we’re not worried about what any one game might be doing. Our sole goal and responsibility is to make Guild Wars 2 the very best game that we can for our players.