The Source SDK has been updated with content and tools to create maps, models, and textures for Half-Life 2: Episode Two, Portal, and Team Fortress 2. In addition to support for games in The Orange Box, the Source SDK can continue to be used to create content for other top-selling Source engine-based games, such as Half-Life 2: Episode One and Counter-Strike: Source.
Included in the Source SDK are:
The Hammer World Editor, which provides the capability of creating custom levels for Source engine games
Valve’s custom Faceposer tool that allows users to produce choreographed sequences in the Source engine
A model viewer that allows artists to preview models and their animations quickly and easily
Source code that allows mod makers to create their own game based on Half-Life 2 or Half-Life 2eathmatch
All of the tools required to make build custom textures and models for Source engine games
Future Source SDK updates will provide new development tools, as well as source code for creating single and multi-player mods that utilize the latest Source engine features.
I might try making something in portal (as the textures and maps in general are pretty basic!)
I hate to think how much detail goes into something with TF2 though, esp if you stand around and look at something like dustbowl for example.
. Will be good if the lighting preview really works though as that was always the worst part of mapping - waiting for it to compile so you could see the lighting.