Alien Arena First Person Shoot
Set perhaps in the future surroundings which are very unfamiliar with little devils for Aliens and many of them. During installation you will be asked the question if you wish to proceed normally the default is (Y/n) under which circumstances you can just press the enter key, however where a package can not be verified it will default to (N/y) in which case if you press the enter key installation will abort. To continue with installation press the lower case "y" instead. You can dispense with the response question by using "-y --allow-unauthenticated" after install and before alien-arena thus:
Installation can be established using the Ubuntu repositories using the install command below, rather than as tarballs from the above download section, however if you would rather install the later versions of this software you may need to install additional Ubuntu packages to compile it with.