Thanks for the replies.
If still necessary after what will be written below, please let me know what info you need exactly.
Paru from repository (version a27.1-5.1, by the way), it says in the link that "Most data created during the game (such as replays, screenshots, and savegames) is stored in ~/.local/share/0ad/", however there are simply 3 empty folders there currently, namely mods, saves and screenshots, no idea where the executable file should be placed.
KDE Plasma version 6.5.3, sdl, if this is what is asked for:
And no, no multiple monitors.
This seems to about describe it, and I am on Wayland, so I need to change Rendered backend from OpenGL to Vulkan? Silly as may be, how would I do that? Do I still need X11, because if so, I think I need to install it additionally?
Thanks.