It was hard for me to connect with Alienoid. I think it likely comes down to cultural differences; certain aspects translate well, while others don’t. This movie just felt too bizarre to me. Its quirky nature didn't help either. The comedic moments didn't land particularly well, and things like giving characters names such as "dogturd" seemed immature. The action sequences were acceptable, but often lacked logic. Characters appearing seemingly from nowhere and concealing themselves behind magical barriers was confusing for this viewer. Ultimately, it seems best suited for the South Korean market; many elements probably draw on Korean mythology, but without a clear understanding of that background, it’s difficult for Western viewers to appreciate.

Source on TMDB