Question

they seemed to enjoy the game change into complex​

Answer 1

They seemed to enjoy the game so that they played for a long time.

Answer 2

Complex sentences have an independent clause and at least one dependent clause.

INDEPENDENT CLAUSE :- An independent clause has the ability to stand alone as a sentence.

DEPENDENT CLAUSE:- A dependent clause cannot stand alone, even though it has a subject and a verb.

SO, your sentence is :-

"They seemed to enjoy the game ."

In complex it will :-

"you seem to be enjoying the game , you should be careful your one mistake will destroy the game. "