Oedipus Rex is a tragedy, a man cursed by prophecy to (Spoiler - click to show)kill his father and marry his mother.
However, that does not have to be the case here. The game gives Oedipus the option to avoid the tragedy of the original play through a series of decisions. Additionally, the game also provides some optional hand-holding. You can choose to have the game guide you down the path of the prophecy or away from it, or an intermediate option which gives you the freedom to make choices and decide your fate.
The story and writing is told well, and does a good job of conveying the world of ancient Greece and the elements of the play. There are some mild RPG and resource management elements here, such as managing your supply of the in-game currency and buying things which may aid your adventures, but nothing overly complicated. There is also a riddle section, as per the original play.
There is plenty of branching and different options within the story, where Oedipus can follow the path of the original tragedy or stray away from it. The game is a little short as far as a single playthrough goes, but there is replay value here. All in all, it is a thought-provoking and enjoyable ride.