It's possible to get Lix via Flatpak.
I recommend a native install over using Flatpak. You should either download Windows Lix normally or get Lix for Linux via your normal package manager. The Flatpak Lix is outdated: It's only Lix 0.10.30 instead of the current Lix 0.10.32. Reason: On Github, the D toolchain for Flatpak is outdated (https://github.com/flathub/org.freedesktop.Sdk.Extension.dmd/pull/85#issuecomment-3624454064), the builds for Flatpak happen with a 4-year-old D compiler, which is too old.
But!
If you use Flatpak, you should know where your Lix directories are. Or, if somebody else uses Flatpak, I should know where he has his directories, for helping and troubleshooting.
Flatpak on Linux:
| ReadOnly: | ~/.local/share/flatpak/app/com.lixgame.Lix/x86_64/stable/
someHexChecksum/files/share/lix/levels/ |
| Writeable: | ~/.var/app/com.lixgame.Lix/data/lix/replays/ |
Flatpak on Windows:
I don't know, nobody has used it there yet.
-- Simon