Atellan farces, Atellanae, were the Roman equivalent of commedia dell'arte of the modern age.
(Unfortunately in JSTOR − check your local university or public library for access) I found this fascinating article: Sulla and the Theatre, Charles Garton, Phoenix, Vol. 18, No. 2 (Summer, 1964) , pp. 137-156.
It discusses not only Sulla and theatre but also the theatre in general in the first century BCE, tragedy, farce, mime, etc., theatre structures, and so on. Sulla's relationship with Metrobius is discussed briefly, but also his patronage of the comic actor Q. Roscius Gallus. New to me was that not only Sulla but also Catulus (Q. Lutatius Catulus Caesar, consul in 102) had an interest in the theatre and that Catulus' step-brother − shouldn't that be natural brother, since Catulus was adopted out? − C. Julius Caesar Strabo, wrote tragedies. Catulus seems to have been an early patron of Roscius. Another section discusses Sulla and the theatre in Greece. The article intimates that Sulla tried his hand on Atellan farces:
"…at some period he tried his hand at writing Latin sketches. They seem to have been atellans, a form which sometime in the past had provided a vent for histrionic high spirits of the ruling classes. Hitherto they had mostly been quite understudied or at any rate unpublished, but in Sulla's time literati began to take them up and make something better of it."
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More on Atellan farces, named after the Oscan town of Atella, "[featuring] the 'crazy' people who lived in Atella, a place where things were purported to happen backwards", can be read at ROMAN DRAMA, Chapter 13: Early Roman Drama and Theatre*. On Sulla:
"…After the fall of palliatae during the early decades of the first century BCE, Atellan farce rose again to prominence, especially in the hands of two pre-eminent dramatists, Novius and Pomponius. These contemporaries of Sulla, who is said have composed Atellanae himself, wrote 'literary' Atellan farces, if such a thing is imaginable."