Well I'll try to do quick outline of compiliation instruction (you'll have to compile if you want newest version, unless someone makes ppa).
First you need some things, you need tools for compling, you can get that by installing build-essentials package, using command line/terminal:
sudo apt-get install build-essential
Then you need dependancies for freeciv, again using terminal:
sudo apt-get build-dep freeciv-server freeciv-client-gtk
Should do it.
Then you download tarball from freeciv site, atchive file that ends in .tar.gz, .tar.bz2 or .tgz . Then you extract it, i would again use terminal. First you navigate there using 'cd' command, then ether:
tar xvf <archive file name>
To extract it, then change to newly created directory, then type:
if all dependacnies are met, you can complie, otherwise you have to see what you'r missing from messages.
this will take quite some time, maybe up to 20 minus, while compiling. If you have multicore machine you can speedup it by using paralel compilation, like:
make -j <number of cores>
instead of simple 'make', obviously cpu usage will be quite high when compiling.
After compilation is done, you can install it:
sudo make install
by default it will be installed in '/usr/local/' (executable at /user/local/bin/freeciv-gtk2). Though that can be changed in configure step. I usually want to have multiple clean versions not interfering with system at all so in configure step I do, something like:
Then after instalation i have all freeciv files there, and launch game using /opt/fc25/bin/freeciv-gtk2
Well thats it for now