Is this a complex sentence? In most countries, people call the game of soccer football.
2 answers
No. It's a simple sentence. It has only one verb -- "call."
Just to be precise, a complex sentence has an independent clause joined by one or more dependent clauses.It always has a subordinator such as because, since, after, although, or when or a relative pronoun such as that, who, or which. Since your sentence does not meet this definition, it is not a complex sentence.