As Raymond Van Dam points out (Remembering Constantine at the Milvian Bridge), one of Zosimus’s main complaints against Constantine was that he stopped the Secular Games (Ludi Saeculares), founded in 17 BC by Augustus and celebrated every saeculum (110 years) since.
“Games” isn’t quite the right word, though. It was a thoroughly religious event: “On the first night the emperor himself was to join a college of priests to sacrifice three lambs at three altars on the bank of the Tiber. On the next day he and the priests were to preside at sacrifices on the Capitoline Hill. As confirmation Zosimus quoted at length the Sibylline oracle that had originally recommended the rituals. In his perspective, ‘as long as all these rituals were celebrated in accordance with custom, the empire of the Romans was protected and they continued to hold our entire world beneath their domination’” (35).
Constantine ended the games, and Zosimus lamented, “because this festival was not maintained, events necessarily evolved into the misfortune that now oppresses us” (35).