Sorry, the AppImage requires at least Ubuntu 20.04.
The reason is I use GitHub Actions to automate the builds. To build AppImages, I use the oldest possible Linux runner that they offer to ensure compatibility with old distros. That was Ubuntu 18.04 until April 2023 when GitHub Actions stopped providing that version and I had to migrate the builds to 20.04.
The other games that still work for you were built on a Ubuntu 18 runner before April 2023.
If you really want to play on old distros, you can compile the game from source.