$ sudo apt-get update
$ sudo apt-get install darkradiant-plugins-darkmod 

darkradiant-plugins-darkmod is installed in your system.

Make ensure the darkradiant-plugins-darkmod package were installed using the commands given below,

$ sudo dpkg-query -l | grep darkradiant-plugins-darkmod *

You will get with darkradiant-plugins-darkmod package name, version, architecture and description in a table

darkradiant-plugins-darkmod package basic information: