At the New York Games Conference last month, Justin Ficarrotta, a game designer and programmer for Freeverse, gave a keynote speech about developing games for the Apple iPhone.

In the keynote, he talked about the pros and cons, the knowns and unknowns, and the dos and don'ts.

Broadly speaking, the iPhone is an extremely attractive platform for student and indie game developers because it has relatively low barriers to entry. It's also new enough in its lifecycle that is still has expansive room for growth and experimentation. Appropriately enough, the title of his talk was "iPhone Games: Bum-Rushing New Platforms For Fun and Profit."

Why i?
Ficarrotta says the two primary benefits of making games for the iPhone as opposed to other major platforms is the cost and the accessibility. "The iPhone has a very low learning curve," he said, and "no absurdly expensive dev kits." (The SDK is free to registered developers.)

To make iPhone games, developers simply have to pay a small registration fee and sign up. "There's no approval process," Ficarrotta said, "It's just 99 bucks to get in." And while developers do have to download an SDK, the only hardware that's needed, according to Ficarrotta, is the phone itself. "If you are holding an iPhone right now, you have an iPhone dev kit."

The software learning curve is minimal, too, Ficarrotta added, but the game design learning curve is still somewhat untested.

Designin for Features and Player Behavior
Like games for the Nintendo Wii, iPhone games have to make use of the unique features supported by the hardware. Configuring the controls is probably the most challenge aspect game developers face, and Ficarrotta devoted some of his talk to discussing some of the tricks he's learned to date.

For example, the multi-touch capabilities of the iPhone are more than just the equivalent of d-pad controls or mouse controls, and trying to recreate those systems on the screen will prove fruitless. There's also no tactile feedback on the device, meaning players can't tell when their fingers have slipped or how far they are "pushing" a joystick-like button.

iPhone game developers are also working with an extremely limited amount of space; "every button that you put on the screen is screen real estate that you take away from your game," Ficarrotta said.

He suggested that developers will create better games if they make use of the ways in which the iPhone can read touch. The phone can track up to five points at a time, allowing all five fingers to be used in the control scheme. "Several touches can be combined into gestures," he said. "Drags, swipes, flicks, pinches, with a variable number of fingers" are the kinds of motions worth experimenting with. "It's very different from what we're used to with mainstream games."

Another suggestion Ficarrotta had for potential iPhone game makers was to not design games that require the player to be totally immersed. The iPhone is a gadget that its owners noodle with during their downtime, while waiting for the subway or waiting in line at the bank, for instance, so it would behoove developers to keep that in mind when designing their games.

The accelerometer (which detects tilting) is another aspect of the iPhone that game designers not only have at their disposal, but are encouraged to make use of in inventive ways. Ficarrotta mentioned that the accelerometer requires very precise handling. It's too sensitive to simply employ as a left/right, up/down control. Popular uses of the accelerometer so far in games have been to use it as a steering feature, wherein the player holds the iPhone like a steer wheel; to orient the phone in the horizontal plane with the screen facing upward and depict a ball on screen being rolled around by the player's tipping motion; and to allow the player to shake the phone in preparation for rolling dice.

However, using the accelerometer motion control is quite different from the using the Wii control, said Ficarrotta, because "you can't see the direct result of your motion" because the hardware that's in motion contains the screen.

The Market
To be a successful game developer for the iPhone, it's important to understand what's going on in its marketplace (and to bear in mind that this space is only a few months old and is subject to many changes in the coming months).

There are two places where developers can place their games, according to Ficarrotta: a free list and a pay-to-download list. The most frequently downloaded games of each list sit at the top of the deck.

But, he said, there is a loophole. Developers occasionally release their game to the free list for a few days or weeks, where its download numbers steadily increase -- and to much higher numbers, relatively speaking, than to the average paid game. Then, the developer moves the game over to the paid list. The download numbers aren't reset to zero when this switch occurs, so the game jumps to nearly the top of the paid games list. (Ficarrotta predicts the Apple team will soon change close this loophole.)

Another important thing to know is that there is no place to offer a demo of a game. However, a common practice among developers is to offer a "lite" version of the game via the free list and put the full game on the paid list.

Other ways games earn exposure are the same as how songs, bands, and albums do on iTunes: a what's new list, what's hot, staff picks.

Graphics and Sound
Ficarrotta noted that OpenGL ES is the solution to most graphics questions about the iPhone, saying it's roughly equivalent to OpenGL 1.5. Mac-specific APIs are also used, and iPhone-specific APIs as well as OpenAL are the options for sound.

A tip from Ficarrotta: "You can (and should) allow the iPod music to play underneath your game sounds."

And when it comes to porting, said Ficarrotta, "for the most part, if you can port your product to your Mac, you can port it to your iPhone."

Ficarrotta also said its worth remembering the iPhone is still just a mobile device, and that many of the lesson developers have learned from creating games for other mobile devices apply to it as well.

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