January 13, 2009


Building Games for the iPhone

January 4, 2009


Almost overnight a lot of apps have popped-up for the iPhone and many of them are games. Quite a few of them look like they were developed by hobbyists over a weekend (not that there’s anything wrong with that). But developing a quality, professional game for the iPhone is still a time-consuming and difficult task.

Once you’ve settled on the game concept, you have to create the play logic, then generate the graphic assets and multimedia. And somewhere along the line you actually have to write the code to make it all happen.

To build a serious iPhone game you currently have several choices:

1. Create a custom one-off app in Objective-C (or C++):

This gives you the most control but it means your game is pretty much going to stay on the iPhone. No desktop version. No Wii. Just iPhone. That might be fine, but if you’re investing tons of hours in content creation and game design, you may want to think hard about whether it makes business sense to leverage all that work and hit more platforms. Building a custom one-shot app also means that all your development effort is only for that one game. Instead, you may want to…

2. Develop a general-purpose iPhone gaming engine:

Where the gaming logic and media content are kept separate and defined in configuration files. This way, you can get two, three, maybe even 100 bangs for your buck. Hopefully, the configuration language is expressive enough so you can build a whole class of apps, not just the same thing over and over. You should be mindful, however, that the iPhone SDK prohibits use of scripting languages, so you can’t embed a Javascript, Lua, or Python interpreter into your code. If you don’t have the know-how or are short on time, you may want to…

3. License a third-party gaming engine:

This takes you away from the pleasure of writing raw Objective-C code (I’m not kidding — it actually is a lot of fun) but it also gives you support tools like 3D modelers, asset managers, physics engines, networking, etc. so you can focus on the high-level logic instead of low-level coding. Most also support some sort of scripting, but get around the SDK restriction by compiling it into executable code.

I have worked on several Objective-C-based iPhone apps so far and developed a custom animation engine for a client, so I have squarely followed options #1 and #2. But I also have ideas for quick, fun entertainment/game apps that I’d like to whip out quickly without spending months on building a custom animation engine. I’d rather spend my time on polishing the game logic and generating nice looking multimedia assets instead of working around iPhone Core Animation’s strange quirks (please, don’t get me started).

So I decided to look around and see what’s out there and came up with the following. To be fair, I haven’t had time to dig too deeply into each one, but as a public service I figured I’d share what I’ve found so far. If I’ve missed any other platforms or made any factual errors, please feel free to post a comment and I’ll issue an update.

Here they are (in alphabetic order):

ShiVa (with the iPhone Authoring Tool) from StoneTrip.

Torque Game Builder (with the iPhone SDK addition) from GarageGames.

Unity iPhone.

In terms of features it’s hard to tell them apart from their spec sheets. They all feature 2D or 3D graphics, support a variety of media and content (including shaders, sound, movies, etc), handle physics and collision detection, and playback audio and video. On the iPhone, there’s also support for the accelerometer (for tilt moves). All three engines support server-based multi-user playing which requires licensing their servers (or their hosting services). It’s not clear at this point whether they support WiFi-based Bonjour peer-to-peer networking which the iPhone and Touch both support.

What differentiates the three engines is what other platforms they support and their pricing model, so let’s dig into that.



ShiVa comes in three versions, PLE, Advanced, and Unlimited (here’s the feature comparison table). The development platform runs under Windows (or Parallels on the Mac). The PLE version is free and allows you to create an application, but you can’t publish the output commercially. For publishing you’ll need the Advanced or Unlimited versions. Advanced costs €169 Euros (approximately $235 at today’s exchange rate) whereas Unlimited will set you back €1,499 Euros (approximately $2080).

The main difference between the two seems to be that the Unlimited edition has additional benchmarking and optimization tools and supports team development. There is no extra cost for output to iPhone (and it looks like they intend to support Windows Mobile and Symbian). You can also target your game so it can run in a browser, but it requires the user to download and install a plugin. A standalone desktop app generator lets you target Windows, Mac OS X, and Linux. However, you’ll likely need to repurpose your media to fit the different screen sizes.

As far as console platforms are concerned, not much there yet.

To support multi-player mode, you’ll need to license the Ston3D Server which comes in PLE, INDIE and PRO flavors. PLE is free but is limited to a single application and 6 simultaneous users. Clearly, it’s intended only for development and testing. The INDIE version runs on Windows, Ubuntu, and FreeBSD, but is limited to 64 sessions (game instances) and 4 sessions per server. It runs €359 Euros (approximately $500) and the PRO server without the session limitations runs €599 Euros (approximately $832).

There are also extra server-side features like managed hosting, payments module, and direct messaging to the user (via SMS, MMS, and email).



GarageGames offers a dizzying array of products and Torque variations, targeted at anything from simple 2D to networked 3D games. The basic 2D package is the Torque Game Builder which runs $100 for Indie apps (those earning less than $250K per year) or $495 for Commercial version. The Pro version also gives you access to the source code for both the engine and the editing tools ($250 for Indie, $1250 for Pro).

If you want 3D support then there’s Torque Game Engine ($150 Indie, $749 Commercial). In both cases, you get a lot of tools that support building levels, media, sprites, etc. and take care of a lot of the low-level grunt work for you.

But that’s not all, Bob. There’s also Torque Engine Advanced ($295 Indie, $1495 Commercial). This gets you all the tools to develop advanced 3D games for consoles and desktops. To deploy your game to a console, you’ll want to look at Torque Wii or Torque 360 (for the XBox 360). License fees for these have to be negotiated.

But it’s the iPhone we care about and to output there, you’ll want Torque for the iPhone. First you’ll need a license to one of the existing ‘builder’ tools (Tool Builder for 2D, or Engine for 3D). for the 2D version, you pay an additional $500 for an Indie license. That lets you publish a single iPhone title. Each additional title you want to publish requires an additional $100 license fee. You also have to show the GarageGames splash screen when the game starts and mention them in the game credits (and app web-site). 3D game support on the iPhone hasn’t been released yet so there’s no price listed.

Want server-based networking? The basic server is open-sourced under GPL. If you want to use it in a commercial app, however, the cost is $295 for Indies and $995 for Commercial apps (consoles are separate). This is for games delivered on Windows, Mac, or Linux. It’s not very clear if networking is supported on the current iPhone version, but I imagine it’ll be there soon.



Unity supports 2D and 3D content with a visual editor to help you develop and design your game content. The underlying scripting technology is based on C# and Javascript but their iPhone Publishing product spits out an XCode project that they claim ‘just works,’ compiling the scripting code into fast ARM assembler code (and thus avoiding the iPhone SDK’s edict against built-in scripting languages).

Under Unity, the Editor is the main point of creating apps. You visually adjust parameters and get live previews, then create scripts to handle game logic. In iPhone ‘preview’ mode, you adjust settings on your desktop screen inside the visual editor and watch it update live on the target test iPhone. It’s a very cool way to quickly adjust and position your objects and verify that they look right on the iPhone screen.

To develop Unity apps, you need the editing system ($199 for Indie developers earning $100K or less — with free 30-day eval, or $1499 for Pro) which lets you generate output for Mac, Windows, browser plugin, and OS X dashboard widget. To output to the iPhone you can got for the Basic iPhone license for $399 for Indie developers and requires showing the Unity splash screen, or $1499 for the Advanced license. Wii/WiiWare output is separate and carries a hefty license fee ($15K-$30K per title).

The Advanced edition also gets you .NET sockets. This means that you can write your own back-end server and aren’t locked into theirs, but you don’t necessarily get Bonjour/WiFi support. You can also stream assets on-demand (which requires an asset-server client license for $499) but I can’t imagine anyone wanting to stream assets unless the user was on WiFi.


There are inherent risks with using a third-party middleware. Will the platform continue to be supported? Are they actively fixing bugs? What happens if they go out of business and you want to continue developing your app? If these are concerns, then you may want to consider Torque’s Pro versions since they come with source code.

On a resource-restricted platform like an iPhone there’s also the matter of having a whole extra layer of runtime between your app and the OS. If your app is going to be pretty media-heavy you may want to roll your own and keep tight control over memory use.

Don’t be scared by these caveats. For certain classes of games these engines will amply make up for the risks by letting you concentrate on content instead of engine technology and getting your app out that much sooner. If used properly, they can also act as ‘force multipliers’ if you are an individual developer or a 2-3-person team. With these tools, you can rapidly create cool apps that would otherwise require a small army of coders and designers.

Which one?


Which one you choose will depend primarily on what features you need, so the first thing I suggest is to download and try out each package (here are direct download pages for ShiVa, Torque, and Unity). All three have free or eval versions and offer Indie pricing for small developers. If your app turns into a big hit and brings in enough revenue, it’s easy to justify the cost of the Pro or Advanced licenses.

If you intend to eventually move to the XBox then Torque is the only way to go. If Wii is where you might be heading, then it’s Torque vs. Unity. All three platforms support standalone desktop apps. I’m not sure with the prevalence of Flash in the browser if anyone’s willing to download and install a browser plugin just to run an application, so I’ll call web-based delivery a wash.

If licensing fees are a concern, then you may want to go with ShiVa. If you only need 2D support, then Torque may work for you (although their iPhone per-app licensing fee is a little too strange for my taste). Mac-only developers will want to look at Unity or Torque Engine Advanced . All others require Windows (but may work under Parallels or VMWare).

iPhone-only features


At this point, nobody seems to support peer-to-peer Bonjour-based networking on the iPhone. Quite a lot of games support that feature. Unlike a Nintendo-DS which allows two players to form an ad-hoc network just by sitting near each other, this only works when all the players are on the same WiFi subnet. It works pretty well when players are in the same room or dorm floor and doesn’t require going out to a central server. It’s especially handy in places where data access is metered and hitting a central server through the cell network can get expensive. Hopefully Bonjour support is something that will be supported soon.

All three engines appear to have decent support for the accelerometer but no mention yet of other iPhone-only features like multi-touch, GPS, or camera. One other thing to keep in mind is that all the license terms and prices listed apply to games only. If you want to develop a social networking or business app you may have to negotiate a separate license.
Bottom line

Remember that regardless of platform, you’ll need to sign-up separately for Apple’s iPhone development program (a $99 cost for individuals) to get a distribution certificate. You’ll also need to do the actual legwork of submitting the application to the app-store. And once the app is out, there’s the matter of marketing and promoting so your app stands out against all those other ones out there.