X-Half-Life Deathmatch 18.104.22.168 Software Development Kit (SDK) (does not include source code)
X-Half-Life: Deathmatch (XDM) SDK
version 22.214.171.124 (updated!)
release 20170301 (installer)
platform Windows 32bit (works on 64bit) - contains executables.
Contains valuable documentation and tools.
Does not contain Half-Life SDK.
Source code is not included and is distributed separately.