Theseus met many unique bandits and monsters on the road to Athens. Among them was Phaia and the Krommyonian Sow. Krommyon was an area near Corinth, right on the road between Epidauros and Athens. The sow was said to be a man-eating pig raised by an old lady by the name of Phaia.
As usual, the ancient texts are not in agreement about Phaia and her monster. For example, Plutarch preserves a version of the myth where there is no beast. Rather, Phaia is a bandit who received the nickname “sow” due to her poor manners and evil life.
Our game most closely follows the account preserved by Apollodorus. In his Bibliotheke, it is said that Phaia was an old lady who looked after the sow, which was named after her. This version is depicted on extant pottery, which shows the lady commanding a giant pig to attack Theseus.
Of course, perhaps all this is just a myth, and Phaia is just a kind lady that poses no danger to Theseus…