Hammer Editor Documentation
Making levels for Counter-Strike: Source
Leaks Explained
Optimizing and Checking Your Map
Controlling Geometry Visibility and Compile Times
Entity I/O
Overview of Prop Types
Physics Entity Overview
Adding Water
Displacement Surfaces (Terrain)
Cubemaps
Ladders
Making 3D Skyboxes
Cables
Making Menu Background Maps
Creating Level Overviews
Using Bspzip to Embed Custom Content
Source Mapping for Half-Life 1 Mappers