First of all, it's not so much an update to the old software as a release of new software, which is free to Halo PC customers.

There are two parts to the new software. One part is a new executable and set of data called "Halo Custom Edition" (haloCE.exe) which will reside in its own separate directory. This new executable includes lots of new features, improvements, and capabilities. It's essentially a collection of many of the things the Gearbox Halo team has developed since the title launched.

Things included in the new executable are "Fast Shaders" (improves performance up to 60% on pixel shader hardware), improved network code (reduces the incidence of player "warping"), and lots of new features that provide options for players to improve their multiplayer games. Perhaps, most importantly, however, the new executable allows end users to play a potentially endless volume of new content created with the Halo Editing Kit.

The other part is the Halo Editing Kit (HEK). The HEK is an exciting package of tools, source material and tutorials that will allow modification makers to bring their own visions to life within the Halo engine.

Halo Custom Edition (HaloCE.exe) and the supporting data is about 200mb and the HEK is about 250mb.