Enemy Mine (1985) - IMDbThe OP says on the previous page, and in his first post, in the PS, that while he did add the words intellectually inspiring and though provoking to the title, he doesn't mind if people add any sci-fi movie to the thread.
Another one: Starship Troopers (1997).
There is a film the name of which I don't remember; it is set in a desert in which there are only two characters, one human and one alien, and throughout most of the movie, they search for and try to kill the other. This is a low budget movie, and doesn't have much action, and if I remember correctly, doesn't have a very high rating on imdb, but many people really liked it.
Chronicles of Riddick & Guardian of the Galaxy are entertaining but certainly not intellectual,inspiring,thought provoking or mind boggling which is the title of this thread.Just add a note saying for entertainment factor as this would help distinguish these movies from various other movies here which really do justice to this thread's title.