Provide an AppImage for Linux

[probonopd]

Providing an AppImage would have, among others, these advantages:

• Games packaged as an AppImage can run on many distributions (including Ubuntu, Fedora, openSUSE, CentOS, elementaryOS, Linux Mint, and others)
• One app = one file = super simple for users: just download one AppImage file, make it executable, and run
• No unpacking or installation necessary
• No root needed
• No system libraries changed
• Works out of the box, no installation of runtimes needed
• Optional desktop integration with appimaged
• Optional binary delta updates, e.g., for continuous builds (only download the binary diff) using AppImageUpdate
• Can optionally GPG2-sign your AppImages (inside the file)
• Works on Live ISOs
• Can use the same AppImages when dual-booting multiple distributions
• Can be listed in the AppImageHub central directory of available AppImages
• Can double as a self-extracting compressed archive with the --appimage-extract parameter
• No repositories needed. Suitable/optimized for air-gapped (offline) machines
• Decentralized

Here is an overview of projects that are already distributing upstream-provided, official AppImages.

If you have questions, AppImage developers are on #AppImage on irc.freenode.net.

[probonopd]

I have made an AppImage but it is trying to load data files from non-existent locations; more investigation needed.

Work done so far:
https://github.com/probonopd/SDLPoP/blob/patch-1/.travis.yml

Edit: Turns out that the code is making heavy use of g_argv[0] rather than /proc/self/exe:

https://github.com/NagyD/SDLPoP/search?q=g_argv%5B0%5D&unscoped_q=g_argv%5B0%5D

Will work around that by cd'ing there before executing.

[EndeavourAccuracy]

There's already a Snap (page, thread), there's already a request for a Flatpak, and now this issue discusses the creation of an AppImage.
Then, of course, we could still ask for a DEB and an RPM.
Linux is such a BS OS.

[probonopd]

Choice is good. The other options don't give a single file that can just be downloaded, moved around, and executed.

[probonopd]

An AppImage can be downloaded for testing:

https://github.com/probonopd/SDLPoP/releases/tag/continuous

Just download, set the executable bit, and run.

Feedback highly welcome.

[johnledezma34]

I tested it in my steam deck using a app image importing app to do so. It works great! Just one issue, I can’t seem to save at all. I got a message on the bottom about quicksave being disabled i think?

[dellmonitor]

SDLPoP creates save alongside binary. AppImages provides read-only directory with binary and data so you aren’t able to save.