Irrational Games is unlikely to ever return to the SWAT series, according to studio co-founder Ken Levine. Prior to the release of BioShock in 2007, SWAT 4 was Irrational's biggest post-millennial success. Now-defunct publisher Sierra asked the developer to make a follow-up, but Levine says this wasn't an idea which inspired them.

"The publisher at the time asked us if we wanted to do SWAT 5, but we just didn't know what else we had to say that was interesting in that space," explained Levine, speaking to at a BioShock Infinite event in LA, last week.

"We felt that we had said what we had to say about that, we didn't know what else to say about it. We were kicking around doing another SWAT game at the time, but we just didn't know what we would do."

The developer did come up with an idea for a SWAT-themed zombie shooter, but the project never reached fruition. Details of the game, including a concept trailer, can be seen on Irrational's site.

And with BioShock being as popular as it is, Levine thinks it's unlikely that Irrational will ever go back to making traditional shooter-based titles.

"You have to really have the craft down to make those kind of games, because there's so many of them that the differences between them are much more imperceptible, so it's really down to this fine-grain quality. Nobody's made a game in a floating 1912 city before, so we could screw up and nobody would know!

"I don't know what the future holds - I never know what the future holds! The marketplace changes all the time, the game-space changes. I have no idea what the next game from Irrational will be. I'm guessing it won't be a SWAT game, but who knows what it'll be?"

Irrational and Levine are currently working on BioShock Infinite, which is due for release next year. You can read our latest impressions of the game in our BioShock Infinite preview.

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