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 -i

Commit changes to git and create tag:
 git commit -a -m "Release version <version>"
 git tag <version>
 git push --tags origin master

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

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