Choosing Your Open Source iPhone Game Engine
Sparrow Framework
The Sparrow Framework is a very lightweight 2D game engine created in Objective-C. In a very short amount of time I was able to understand the framework, and I find it to be very intuitive.
If you’d like to take a look at some actual coding with the Sparrow Framework be sure to check out the Beginners iPhone Action Game Programming Tutorial.
While I have not done much Flash game programming the developers state that the game engine was created with Flash game developers in mind.
The game framework includes all the necessary features you’d require for creating a basic 2D game such as easy animation, and a sound engine.
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Cocos2D IPhone
The Cocos2D iPhone game engine is a port of a game engine originally created in Python and converted to iPhone Objective-C. As you can tell from the name, Cocos2D is designed for 2D games, that being said, although the engine is in a 2D world, the engine includes a growing collection of high quality 3D special effects.
Cocos2D has been used in many games on the iPhone app store, you can visit the official site here, where many are listed.
Cocos2D is the first engine to check out, while many may be turned off by the engine not supporting a 3d world, if you look at most of the top iPhone games the gameplay is 2D, in fact the iPhone’s touch screen controls can make it difficult to operate in a 3D world.
Also included is support for the in-game Chipmunk engine, and the latest version of Cocos also includes an OpenAL based sound engine.
The engine provides more examples than any of the other engines out there because of the large community. Overall I’d say the engine is as easy to use as any engine that does not have an environment editor.
Uses the LGPL license.
Sio2Engine
The SIO2 game engine is an excellent 3D game engine written in C. There is a free oepn source version, and a an indie version for $49. The free eidtion requires you to show a splash screen at the start of your game illustrating your use of the engine. This in my opinion is extremely fair considering the quality of the engine.
The game engine uses blender in it’s toolchain for scene and model creation. If you haven’t used Blender, it is a sophisticated open source 3D modeling program. In my opinion this is the only thing I don’t really like about sio2, while some love it, I can’t stand using blender as I’ve found it can’t compare to the top commercial modeling programs. Fortunately there are many blender plugins that allow you to import a wide variety of modeling formats.
SIO2 comes with an excellent set of tutorials, and provides support for sophisticated features such as skeletal animation, and soft-body physics which are explained in the tutorials.
I’ve found the performance of the latest version of the SIO2 game engine, version 1.4 to provide significantly better performance than previous versions. If you haven’t checked out SIO2 in awhile then I suggest you check it out again.
I recommend SIO2 to those who insist on a 3D world and thus can’t use Cocos.
Oolong Engine
The Oolong game engine is a 3D engine written in C++, and provides excellent performance. The downside of the Oolong engine is that it is difficult to use for those that are not familiar with OpenGL ES.
Oolong provides support for a wide variety of features, and very good performance, as I said my only problem with Oolong is that it is difficult to use. This is a low-level engine designed for programmers so if you’re just getting into game development I would stay away.
You will find the latest version on google code, there is very little documentation for Oolong, but the community is very active, and you can get answers to many of your questions there.
I would recommend Oolong to those looking to create their own game engine looking for something to start with.
Uses the MIT license.
Irrlicht Engine
I mention Irrlicht here only because I received a message from someone stating that it was available on the iPhone. I know that it has been used in the creation of apps already available on the iPhone.
The Irrlicht game engine is a 3D game engine written in C++.
While there is no official port available on the Irrlicht website for the iPhone with some tinkering I was able to get the OpenGL ES version running on the iPhone — somewhat. You will find the OpenGL ES version hidden away in the repository.
Irrlicht is an excellent open source engine that has support for an extremely wide variety of file formats, and has the best support for the “classic” BSP format that I’ve seen in an open source game engine. There are also numerous other tools that have been created for the engine.
All this being said, I can’t recommend Irrlicht because there is no official port, and if you check out the forums there really is no one willing to provide help to those looking to get it running on the iPhone although some have created apps running on the iPhone.
The Irrlicht engine uses the Zlib license.
Summary
The Sparrow Framework makes an excellent first choice for those developing a 2D iPhone game. Cocos2D is the most popular, and has the most support but is less intuitive. You will learn Objective-C while using the engine, and the engine has been proven in a wide variety of games.
For 3D games my choice is SIO2, although I’m not a fan of blender this does make it more accessible than the other proven 3D iPhone game engines.