Types of Verbal: Participial Phrase Verbal Phrase: requiring much patience and skill
A participial phrase uses a verb as an adjective. In this sentence the phrase "requiring much patience and skill" modifies the noun game making it an adjective. It then helps to describe the type of game chess is.
When finding verbal phrases, it helps to identify the subject and main verb phrase of the sentence. In this sentence the subject is Chess. The main verb is the linking verb is. Then look for other verbs in the sentence. In this case requiring is the second verb. Double check to make sure the subject is not doing the verb. Chess is not requiring so this means that the verb "requiring" is the beginning of the verbal phrase.