The usage of unlike

I came across this article today.

Unlike in real life, in a dramatic participation, all the protagonists call on the spectator to be absorbed by him and to identify himself with each of them.

“Unlike” is preposition, right? In the basic rule, prepositons are followed by nouns. But I know that there are many sentences in which “unlike” is followed not by nouns but by prepositional phrases. So is it okay for me to understand that “unlike” has a very unique usage, unlike other prepositons?