While talking with the dev team about Planetside 2 at Fan Faire this past weekend, SOE president John Smedley and Creative Director Matt Higby listed EVE Online and Battlefield 2 among outside games that have inspired their designs for Planetside 2.
Smedley plays EVE Online regularly and frequently mentioned it as the major influence for the sandbox portion of PS2. Its influence is obvious in both PS2's time-based, offline skill progression system and the desire to have a single shard server, even if Smedley said that they probably won't be able to manage that until awhile after launch, when there are multiple planets. "We're probably going to end up with [separate] servers," he continued, "but we're going to experiment with [single shard] internally to see what we can do with it." It's an interesting idea, and there's a lot of great potential in having the meta-game played on a single shard. It's easy to imagine the same type of large-scale territorial control schemes that pop up in EVE replicated in Planetside 2.
Both Smedley and Higby mentioned FPS games as inspiration, including the Battlefield and Call of Duty series, and Higby specifically mentioned that Battlefield 2 (and what he's see so far of Battlefield 3) is "definitely on a pedestal" as the pinnacle of vehicle combat in multiplayer. He feels that "they've done the best with vehicles. I want to be at least that good."
I'm quite fond of the games that they both mention, and it seems to be a good big-picture way of picturing PS2's main elements. You don't often hear EVE Online and Battlefield: Bad Company 2 discussed in the same interview, but it seems like an apt combination of gameplay styles for Planetside 2's big dreams of shooter-powered territory control warfare.