Casual-centric features are necessary for the longevity of World of Warcraft, lead designer Tom Chilton told Polygon during this week's Gamescom event in Germany.

Blizzard made its first major push to appeal to casual fans with last year's release of expansion Mists of Pandaria, something that Chilton says has proven to be "very successful" for the company.

"We would have been in bad shape had we not done that," he told us, acknowledging that many long-time players saw this move as a break from the MMO's roots which focused on instances and raids. With reference to the original World of Warcraft before the release of any expansions, Chilton said:

"People who played Vanilla always say 'if it had stayed the same, I would have the same fun now as I did then.' But that's not true. Audiences always evolve," he explained.

The studio worked to provide players with new experiences with the introduction of "dungeons, raiding, the introduction of accessible raiding," with the adoption of casual features simply being another layer to this. Chilton did, however, acknowledge a lack of "new experiences for the hardcore audience," stating it's something that will be focused on at a later date and is likely something that will be introduced through future expansions.

Blizzard is no longer opposed to the idea of re-inventing the MMO as a free-to-play title, Chilton added, although the team is still unsure of the success rate of free-to-play games over time.

"For Blizzard it makes sense [to go free-to-play] at some point. But a lot of the risk is in making that transition. You hear stories about developers going free-to-play and getting double the number of players, but you don't always know it works out that way and how long it stays that way. We really don't know what the rate is before people drop off and lose interest."

World of Warcraft's next major patch 5.4 is scheduled to release on Sept. 10.