Formerly named Agape, GameImage is a way to package up games with either Wine or an Emulator into a portable AppImage that could be useful for the Steam Deck. I could have sworn I wrote about this before, but apparently not. Edit: it was Winepak I was thinking of previously.
As the developer on the project explains, emulation is popular and with the Steam Deck here people are doing a lot of it. However, configuration can be an issue, with files getting messed up or going missing and so GameImage aims to help with that as it packages up a runner (like an Emulator or Wine), a game and it's configuration files into a single AppImage.
Now, I should note, there's some obvious legal stuff around this that could cause issues with people sharing their creations with it that could contain full games. So it's of course something more for personal use. That, or you could share creations without the game perhaps for people who just want the configuration all set up and ready for you to slot your game files into after.
Another problem though is bloat. For the Steam Deck especially, drive space is always a concern. Every AppImage made with GameImage would contain duplicates of whatever emulator or Wine version being used, which is the point though, since it's all about being self-contained and easy to run anywhere be it a Steam Deck or desktop Linux. It does use squashfs, which will compress them to save a bit of room.
It currently supports RetroArch, PCSX2, RPCS3, yuzu and Wine. It also supports having a proper logo for each AppImage too, as the developed showed in their example:
What do you think about this tool?