Build a base, defend it against the other team, gain credits for better weapons or more advanced aliens, try to wipe them out.

Packages are available for the following releases:
Ubuntu 16.10: 0.50.0-1~getdeb3~yakkety
Ubuntu 16.04: 0.50.0-1~getdeb2~xenial
Ubuntu 14.04: 0.46.0-1~getdeb1
Ubuntu 14.10: 0.38.0-1~getdeb1
Ubuntu 15.10: 0.50.0-1~getdeb1
Ubuntu 15.04: 0.44.0-1~getdeb1

Package downloads per version:
Version 0.38.0: 76
Version 0.44.0: 129
Version 0.46.0: 685
Version 0.50.0: 1231

Install the application manually with the following command:
sudo apt-get update && sudo apt-get install unvanquished

Uninstall the application with the following command:
sudo apt-get remove unvanquished