The House of Atreus Act I, released in 1999 is the first part of a metal opera inspired by the  only extant example of an ancient Greek theatre trilogy which won first prize at what festival?
Oresteia The Oresteia (Ancient Greek: Ὀρέστεια ) is a trilogy of Greek tragedies written by Aeschylus concerning the murder of Agamemnon by Clytaemnestra, the murder of Clytaemnestra by Orestes, the trial of Orestes, the end of the curse on the House of Atreus and pacification of the Erinyes. The trilogy—consisting of "Agamemnon" (Ἀγαμέμνων ), "The Libation Bearers" (Χοηφóρoι ), and "The Eumenides" (Εὐμενίδες )—also shows how the Greek gods interacted with the characters and influenced their decisions pertaining to events and disputes. The only extant example of an ancient Greek theatre trilogy, the "Oresteia" won first prize at the Dionysia festival in 458 BC. Many consider the "Oresteia" to be Aeschylus' finest work. The principal themes of the trilogy include the contrast between revenge and justice, as well as the transition from personal vendetta to organized litigation. "Orestia" originally included a satyr play, "Proteus" (Πρωτεύς ), following the tragic trilogy, but all except a single line of "Proteus" has been lost.
Lysistrata Lysistrata ( or ; Attic Greek: Λυσιστράτη , "Lysistrátē", "Army Disbander") is a comedy by Aristophanes. Originally performed in classical Athens in 411 BCE, it is a comic account of a woman's extraordinary mission to end the Peloponnesian War by denying all the men of the land any sex, which was the only thing they truly and deeply desired. Lysistrata persuades the women of Greece to withhold sexual privileges from their husbands and lovers as a means of forcing the men to negotiate peace—a strategy, however, that inflames the battle between the sexes. The play is notable for being an early exposé of sexual relations in a male-dominated society. Additionally, its dramatic structure represents a shift from the conventions of Old Comedy, a trend typical of the author's career. It was produced in the same year as the "Thesmophoriazusae", another play with a focus on gender-based issues, just two years after Athens' catastrophic defeat in the Sicilian Expedition. At this time, Greek theatre was a profound form of entertainment, which was extremely popular for all audiences as it addressed political issues relevant to that time.