Immortals is an action-adventure video game played from a third-person perspective. At the beginning of the game, players can customise the gender, the voice and the appearances of Fenyx using Aphrodite’s Beauty Chair. At any point in the game, they can return to the beauty chair and customise Fenyx. The game is set in a large open world, consisting of seven distinct regions inspired by the Greek gods. The player character is accompanied by a companion bird named Phosphor, which can identify locations of interest in the map. Fenyx can traverse the world quickly through climbing cliffs, riding on a mount, and flying using the wings of Daedalus. The full open world will be accessible from the start of the game. As players explore the world, they would encounter rifts which would teleport them to the Vaults of Tartaros, which are a series of platforming challenges that require players to utilize both Fenyx's combat and traversal abilities. Players can also complete various side-objectives and optional puzzles.

The world of the Golden Isles are occupied with various enemies inspired by Greek mythology, including minotaurs to cyclopes. There are two modes of melee attack; light attacks with a sword are fast but weak, and heavy attacks with a hammer are slow but strong. Fenyx can also use bows and arrows to defeat enemies. Players need to manage Fenyx's stamina during combat, as they will become exhausted when they attack successively. As players progress in the game, they would be able to unlock powerful godlike abilities. For instance, Fenyx can unlock Ares' spears which thrust enemies into the air. Armor and weapons can also be upgraded by collecting sufficient crafting resources in the game's world.

Story

After spending eons imprisoned under a mountain by Zeus, Typhon manages to escape and takes his revenge on the Olympian gods, severing them from their godly essences and robbing them of their powers. Zeus flees and meets Prometheus, seeking to secure his aid in battling Typhon. Prometheus instead makes a wager with Zeus that if Typhon can be beaten by a mortal, then he will be freed from his imprisonment. Otherwise, Prometheus will agree to help Zeus. Prometheus then uses his power of foresight to tell the story of Fenyx.

Fenyx, a young Greek shield bearer, barely survives a shipwreck and washes up on the Golden Isle. They are shocked to find the surviving crew and the Golden Isle's residents turned to stone. After recovering several artifacts belonging to legendary Greek heroes and receiving a prophecy, Fenyx rescues Hermes, who informs them about the situation and the grave threat Typhon poses, as he seeks to break the barrier between the mortal realm and Tartaros and reform the world in his own image. Determined to stop Typhon and save humanity, Fenyx agrees to venture out into the Golden Isle to restore the deposed Olympian gods. Through their efforts, Fenyx befriends a magical bird companion named Phosphor and manages to restore Aphrodite (who became a tree without her passion), Ares (who turned into a rooster without pride), Hephaistos (who became one of his automatons without suffering), and Athena (who turned into a child with no judgement). Fenyx also defeats the spirits of Achilles, Atalanta, Herakles, and Odysseus, who had all been corrupted by Typhon.

However, despite the gods having been restored, they quickly begin to fall to bickering and infighting when they cannot agree on a plan to stop Typhon. Fenyx's older brother Ligyron, who somehow escaped the petrification curse, then arrives and tells the gods of his plan to steal Hephaistos' chains from Typhon, enchant them using the blood of the gods, and use them to imprison Typhon once again. The gods agree to Ligyron's plan, but Fenyx is frustrated that he refuses to bring them with him in order to protect them from danger. However, the gods encourage Fenyx to go after Ligyron so as not let him steal the glory Fenyx deserves.

Fenyx scales the mountain at the center of the Golden Isle and manages to witness Ligyron collaborating with Typhon, collecting all the ingredients necessary to create a poison capable of killing the gods. In return, Typhon will allow Ligyron to become a god in his new world and rule the Golden Isle. Fenyx confronts Ligyron and defeats him, forcing Ligyron to flee to Tartaros. Fenyx follows him and confronts Typhon himself, being able to best him battle. With his last breath, Typhon reveals that Fenyx is actually a demigod and Hermes' child.

Throughout the story, Zeus comes to realize how much he has mistreated his children and the other gods, and becomes regretful at how he had become such a poor parent and husband. However, he interrupts the story when he hears Fenyx is supposed to be Hermes' child, pointing out it should not be possible. Prometheus then admits that he had manipulated and fabricated parts of the story. He arranged his Titan brother Atlas to free Typhon and shipwreck Fenyx on the Golden Isle. In addition, he hid details that Fenyx is actually one of Zeus' children, and that in reality, Typhon told them that it was Zeus who turned all of humanity to stone. At that moment, Fenyx arrives with Typhon's poison, confirming the entire story was part of Prometheus' plot to have Zeus killed.

Zeus admits that even though he created them, he wanted to destroy humanity due to their flaws, but has come to realize that humanity's flaws are merely a reflection of the flaws the gods and he himself possess as well. He feels he doesn't deserve to live and doesn't put up any resistance. However, Fenyx reveals they don't have any intention of killing Zeus, instead wanting to inspire him to be a better father to his children and a better god. Typhon then reappears, furious that Fenyx will not kill Zeus as planned. He consumes the poison to empower himself and captures Zeus, taunting Fenyx to come and try to stop him. Fenyx follows Typhon back to Tartaros and battles Typhon again, but Typhon manages to slay Phosphor and Fenyx begins to lose ground against him until Zeus escapes and rallies the other gods to come to Fenyx's aid. Working together, they are able to defeat Typhon once and for all, as he succumbs to the very poison he consumed.

Afterwards, as reward for helping defeat Typhon, Zeus agrees to return humanity to normal, restores Phosphor as a new creature, the phoenix, and invites Fenyx to live on the Golden Isle with the gods. Fenyx agrees, as long as they get to keep an eye on Zeus to make sure he's committed to becoming a better god and father. Meanwhile, Zeus sends Ligyron to free Prometheus as part of the wager, but not before tormenting Prometheus by having Ligyron tell his own story of Fenyx, much to Prometheus' annoyance.