HammUEr, a Hammer/Worldcraft map importer for Unreal Engine

[turfster]

@Beaucephal;488769

Is there a way of running Hammer and editing, say, HL2 content without having to install the full SDK, or is it an all-or-nothing type of affair?

You can install just the authoring tools for certain Source games (L4D1 or 2, Portal 2)
Pretty sure a HL2 install has hammer installed in the \bin directory by default.