I just installed it and in a terminal executed it and got the command
help printed out. I then entered the command "locate alien" and got the
response here.
/usr/share/app-install/desktop/alien-arena.desktop
/usr/share/app-install/desktop/alienblaster.desktop
/usr/share/app-install/icons/alien-arena.png

I hope this helps, or you could use synaptic to remove it and then
reinstall it, then in terminal window enter the command like I did.