As the title says, I can't seem to be able to enter combat mode. Tried the demo first, bought the game from GoG, and for some reason I can't even find the combat mode listed in the key binds list. What gives?

That is strange. One possibility is that the full version has tried to use the demo's configuration files. Try uninstalling the game and deleting anything left in the target folder. If you're using Vista or Windows 7 you will also need to clear out the VirtualStore files it has created, which will be located in %LOCALAPPDATA%\VirtualStore\Program Files (x86)\GOG.com\Arx Fatalis (or similar--the path below VirtualStore reflects wherever it was installed to). Then reinstall.

Tsk, stupid me. I tried to click the arrows in the key binds list to move to next page, but it never worked, so I thought there was only one page. Finally managed to click it. I think the hotspot is one pixel in size, since it took so many tries. Anyway, that's where the command is, unbound of course.

Thanks for the help though, appreciate it.