Unreal Engine Technology
- Official Unreal engine 4 site. Contains documentation, development forums, Answer Hub, and, the most interesting - full access to the engine source code and demo content, just for $19 per month.
UDN - Unreal Development Network
- Official Epic Games site with Unreal engine documentation. Part of information is in a private access (relative to the console and C++ development). Mainly for information about UE3 and 3.
- The Unreal Wiki is dedicated to gathering documentation on the Unreal Engine. You browse the large quantity of material already here. Anyone can add or edit information instantly. Useful mostly for UE1 and 2 developers.
- Open-source Unreal level viewer for Unreal1, UT99, WOT, Unreal2, UT2. Not updated since 2005.
- Delphi unit, which allows you to read Unreal engine package files. Supports Unreal Engine 1 and 2 packages.
- Script decompiler for some UE3-based games. The development were stopped in 2009.
- Another one UnrealScript decompiler. Has nice GUI. Under active development.
A tool for research and modification of Mass Effect 3 content. Open source. Under active development.
Here are some links with unofficial documentation about Unreal file formats prepared by other people.
- A tool for modification of XCOM packages. With source code.
- Unreal engine related news.
- Player models for all Unreal series games.