AppImage packaging

[TheJJ]

We should provide easy support to create an AppImage for openage.

https://github.com/probonopd/AppImageKit

Maybe there are other similar approaches, we should also work towards supporting them.

[probonopd]

The https://portablelinuxgames.org/ project is packaging games in AppImage format.

Please note that compiling the binaries on a not too recent build system, e.g., CentOS 6, is the preferred method for AppImage generation. The reason is that (as a general rule) the AppImage will be compatible with distros that are no older than the build system.

More information on https://github.com/probonopd/AppImageKit/wiki/Creating-AppImages

[TheJJ]

Does the "build system" include the compiler version or just the autocancer, cmake, make, ... versions?

[probonopd]

Mainly the libs. For example, a CentOS 6 build system using a newer compiler, cmake, make,... has worked well for me. A newer glibc, however, is problematic.

[Hiradur]

It'd be great if the AppImage would not only contain builds for Linux but also for other OS/architectures such as Windows and macOS similar to how Xonotic and OpenArena do it. This way it's very easy to share the game and ensure everybody is using the same version at e.g. LAN parties regardless of which operating systems are used. The players then only have to drop their AOE 2 data files into the extracted archive and can start playing.

[simonsan]

Here are some updated instructions for using OpenSuse Build Service (OBS):
https://docs.appimage.org/packaging-guide/hosted-services/opensuse-build-service.html#ref-obs

or packaging manually:
https://docs.appimage.org/packaging-guide/manual.html