XNA is the main official developer tool released by Microsoft to develop applications and games for Zune and Zune HD music players. However, XNA does place a few restrictions and blocks accesses to several content areas. In order to make game development for the mass, no 3D and no Internet access are allowed on Zune, and the game may have performance penalty when running on Zune, despite Zune is equipped with hardware, especially Tegra processor that can do better.
With the release of OpenZDK (Open Zune Development Kit), all Zune models including Zune HD has been hacked. OpenZDK is first known hack for Zune, and allows native applications to run on top of the Zune firmware, with full access to all hardware features which previously been locked by XNA. In other word, OpenZDK opens the opportunity for homebrew (unauthorized) apps, games, 3D games based on OpenGL ES 2.0 support, ports of classic games, app stores, emulators and just about anything else to run on Zune.
In essence, OpenZDK is a development tool without limitations of XNA to develop applications and games specially for Zune. So it’s not jailbreak, unlock or rooting tool, as the original Zune and Zune HD devices are not locked. The initial release of OpenZDK is primarily intended to give developers a starting point for building next-generation applications. OpenZDK opens the possibility for more developers to create and port games for Zune platform.
As OpenZDK has just been released, few apps have actually been built on it. Currently, the hackers have published an OpenZDK Quick Start Kit that includes example programs that Zune users can try right now, including a 3D demo that offers a small taste of what hardware-accelerated 3D graphics have to offer.
Above file would be of interest to developers though, end-users who want to install OpenZDK applications need not do anything, if the Zune have deployed an XNA application, which also requires the prerequisites to be installed. Zune players preceded Zune HD also also need to install and run the Exploit Deployment Tool. All instructions are available on zunedevwike.org.
Developers are encouraged to post their OpenZDK applications at the new dedicated forum on ZuneBoards, so end-users can download the new OpenZDK apps from ZuneBoards, if any.
The new Kin phones from Microsoft will also be running some of Zune software, but the phones have been locked down. So the OpenSDK cannot be simply ported to the Kin phones.