What started as a lark, playing around with an operating system that would allow Doom creator John Carmack to quickly produce portables games, has become a thriving business, the famed developer tells Kotaku.
"Wolfenstein Classic was my original experiment on whether a first-person shooter would be any fun on the iPhone," he said. "It did surprisingly well for all of us."
So well, in fact, that Carmack finds himself spending a disproportionate amount of his time working on future iPhone games. Already id Software has released Wolfenstein Classic, Wolfenstein RPG, Doom Resurrection and this week Doom Classic.
Carmack said that there was a lot of "hand wringing" initially over the idea of spending the company's own money (there was no publisher to help fund development) on making games for the iPhone. Doom Resurrection, when it hit, was probably the most expensive game to develop for the iPhone, Carmack says.
But that internal concern quickly disappeared when Wolfenstein Classic hit the App Store.
"It did really well for us," he said. "It was Wolfenstein Classic that made the argument for iPhone development for me. We made quite a bit of money off of that."
After its success Carmack and id Software decided to launch a three-prong approach to iPhone development, working on classic remakes, role-playing titles and original games.
With only a few games out for the platform so far, each game gives Carmack a chance to experiment with development and the technology, he said.
While Doom Classic's touch controls may seem very similar to those found in Wolfenstein Classic, Carmack says there's quite a big difference.
" There were some important changes, like the virtual stick autocentering, changes to precise ramping of movement," he said.
The game also introduces a new control option that allows gamers to turn around in the game by spinning a virtual wheel. But only six months into iPhone game development, Carmack says he already finds himself "hamstrung" by people's expectations of controls set by his previous games.
"We're still feeling out what will play well and what people will like," he said.
Next up for Carmack is Quake Classic, it will be the first shooter that id Software releases for the iPhone that will include the ability to look up and down, not just side to side.
I pointed out that some in the gaming and development community have suggested that both Doom and Wolfenstein Classic control so well because they don't need to worry about up and down controls.
Carmack said that while adding another axis of control is tricky, it would be wrong to dismiss what the current games have accomplished.
"There is an excellent experiment that can be done here," he said. "Play the jail broken Doom and the one I worked on. There is obviously a large difference here. You can be dismissive of the game, that there is a limited control input set, but there is a lot of work that goes into that.
"Everything that has a 32-bit processor has had Doom ported to it, you can run it on a toaster, but it takes a lot of work and care to turn it into something you would choose to play. I had people showing me FPS apps while I was working on Wolfenstein, and they were all atrocious."
Carmack says that it is possible that a fully controlled first-person shooter just isn't in the cards for the iPhone, but he won't really know until he's developed Quake Classic. After that he plans to work on Quake 2 for the iPhone.
"I'm not sure if after Quake 2 I want to do Quake Arena or Quake Live for the iPhone," he said.
The problem is that while Quake Live has better levels it would require WiFi to play online. That's because 3G just won't cut it for Carmack.
"I was originally excited about 3G," he said. "I was told it could have 180 pings, but when I tested it, it was twice that. It was not usable."
While the Classics' line seems fairly mapped out, Carmack isn't as sure about the RPG and original games coming from the developer. He says that the next RPG game will be Doom 2 RPG and if that does well they will move on to the Orcs and Elves RPG games.
The only other original game announced by id Software is one that will be based on their upcoming PC title Rage, but that doesn't mean there aren't others in the works. In particular Carmack is interesting in getting parent company Bethesda interested in bringing some of their games over to the iPhone.
"I spent a bit of time talking to Todd Howard about the iPhone," he said. "We want to make something happen for those products as well."
An obvious choice would be Fallout, something that Carmack says has already had internal proof of concepts made. But nothing has yet officially happened with the game.
Carmack says that Howard, a big fan of the iPhone, is very supportive of the idea and that anything made based on Bethesda's games would likely be created as a joint project between id and Bethesda.
He added that he would be involved in making the game most likely, but that his time is "overloaded badly right now".
"At the very least I'm going to be providing code," he said.
While more people are being brought on to help with iPhone development at id Software, it's clear that Carmack wants to stay involved with the growing business.
"I've had tons of fun working on it as a platform,"he said. "I carry an iPhone around with me as my regular phone all of the time. It's like carrying around a dev kit in my pocket."