Treyarch wasn't really interested in the business of making mobile phone games, at least not before the iPhone.
But the tremendous success of Call of Duty: World of Warcraft: Zombies on the iPhone has the developer, best known for their hardcore console shooters, reconsidering.
"We are very interested (in bringing more games to the iPhone)," said Josh Olin, Treyarch's community manager. "It has treated us well."
Zombies rode the top of the charts for paid download apps on iTunes for a number of weeks, and the $13 game hit the top again after a free, lite version of their shooter was released.
Today the company is rolling out an add-on pack for $US5.
Both the original game and the add-on were developed in conjunction with London-based studio Ideaworks.
"They have a lot of experience developing iPhone games," Oline said. "We had this zombies idea for the iPhone that we wanted to bring to the mobile platform and make coop centric."
So Treyarch gave Ideaworks all of the original assets from the console versions of the game, which was an unlockable multiplayer add-on for the home console version of Call of Duty: World at War.
"They iterated on that and made it work," he said.
Treyarch is already examining what they might bring next to the iPhone.
"Call of Duty: World at War coming to the iPhone is a definite possibility," he said. "That would be a natural fit."
Olin dismissed the notion that the iPhone and iPod Touch aren't "real" gaming platforms.
"Personally, I think it's a great platform," he said. "It's really powerful. It's right on par with what you are seeing with other handheld consoles. That's full 3D running on Zombies, none of that cheating sprite technology. It's all real tech in the game."
And each new iteration of the iPhone has gotten more powerful, he added.
Despite Treyarch's new-found interest in the iPhone and iPod Touch, the developer remains bullish on Apple's upcoming iPad, deciding to hold out on development for the new platform until they have more details.
"I don't think we have crossed that bridge yet," Oline said. "It's way too new a product."