What is the ruling on using the word "إله" (god) when referring to other than Allah Almighty, while being certain that there is no god but Allah, such as in the names of some movies, novels, or games like "God of War"?

It is impermissible to be named "al-Ilah" (the God) because it is a name exclusive to Allah Almighty, and it is the origin of the name "Allah," derived from "al-Ilahah," meaning worship. However, reporting that someone was named "al-Ilah" or described as such—while believing in the invalidity of this—is not forbidden.