Here is small HOWTO release new version of Stratagus (and also Wargus/War1gus/Stargus/...)

Increase version in file:
 CMakeLists.txt

Update changelog in file:
 doc/changelog.html

Increase version and update changelog for debian:
 dch -vNEWVERSION
 dch -r

Update copyright information for Debian:
 debian/copyright

Update Copyright information in NSI installer:
 src/win32/stratagus.nsi

Tag the new release in https://github.com/Wargus/win32-stratagus-dependencies
and wait for it to run through on the Appveyor CI. This will automatically
cause a release with the tag name to be created, and the windows dependencies
will be uploaded there.

Tag the new release here and wait for it to run through the CIs. Appveyor and
Travis will upload new versions for Windows and OSX, and Launchpad will
automatically build new debian packages:
 git commit -a -m "Release version <version>"
 git tag <version>
 git push --tags origin master

For Wargus/War1gus/Stargus we have a release.rb script. Run it without any
arguments, and it will tell you how to call it to start the release process
for this particular project.

Tag the new release in Wargus/War1gus/Stargus/... these repositories should be
set up to also use the appropriate release source from the Stratagus releases.