Shadow Of Rome has two main types of gameplay. Firstly, there are weapons-based close quarters combat levels involving Agrippa that takes place in various gladiatorial arenas throughout the Roman empire. Secondly, there are stealth-based puzzle-solving adventure levels (intermixed between the combat ones) involving Octavianus that take place in the vicinity of Rome's bases of political power. In addition to these two main gameplay types, there are a few levels where the player controls Agrippa in chariot races. The viewpoint is third-person perspective behind the hero. Shadow Of Rome can be played at 'Normal' or 'Hard' difficulty levels. Additionally, once the game is beaten on both these settings, a new 'Extreme' difficulty becomes available.
The game is sectioned into four chapters. They are: "The Wickedness of Men", "Baptism by Fire", "Wrath of the Gods", and "Restoration to Glory". As the game progresses, Agrippa encounters different types of weapons to use, with the ultimate weapon being the Great Sword (also known as Magnus). These weapons break after repeated use, adding realism to the game. Also, during Octavianus' levels, the player can collect special coins (silver and gold) that allows the player to purchase special items from the various merchants at the City Gates. These items are, mainly, just decorations for Octavianus' room. Also, buying a certain number of items unlocks special costumes which Octavanianus can wear (Mr. Onion Head, Pansa's Robe, Splitting Headache, & Chameleon Suit). Achieving certain ranks in the arena battles (Bronze, Silver, or Gold) on the various difficulty levels will unlock certain secrets like various mini-games and different cheats. Plus, completing an arena battle unlocks it in the Battle Selection menu. So, the player can, basically, re-play any arena battle over again to earn a higher rank or just for fun.
A Salvo is a unique combat technique that Agrippa may perform during battle. Performing multiple different Salvos within a short time period increases the audience's excitement, and increases the chance of them throwing newer, more dangerous weapons to Agrippa for his use.
The frequent acquisition of formidable new weapons from the bloodthirsty onlookers is a must, since a player's current weapons have only a limited durability, and so break after a few strikes/blocks. Again, 'Salvo strings' become a very essential part of surviving later on in the game. Some of them are unique in that they can only be performed in certain events, or against certain foes. Also, achieving a certain total number of Salvo points will unlock armor upgrades for Agrippa (300,000 points for the Fortus Rex armor and 800,000 points for the Talon Aegis armor).
- Caesar - The most respected and famous military and political leader in the history of the Roman Republic, his paternal image and warmth earned him the respect of his subjects. On March 15th, on his way to the Senate House, Caesar is attacked by an unknown assailant and dies at the feet of a statue of Pompeius. His last famous words were "Et tu, Brute?".
- Agrippa - Caesar recognized the military genius and fighting instinct of Agrippa and appointed him Centurion at a young age. He counts Octavianus among his friends. Accused of Caesar's assassination, Agrippa's father, Vipsanius, is arrested by the military. His mother, Vipsania, is then publicly executed at the hands of Decius. It is decided that the winner of a gladiatorial tournament held in Caesar's honor will be Vipsanius' executioner. Agrippa immediately makes plans to enter the tournament.
- Octavianus - Having lost his father at a young age, Octavianus was adopted and raised lovingly by Caesar himself. He is a close friend of Agrippa. When news of Caesar's assassination reaches his ears, he rushes back to Rome only to find that the man who stands accused of the murder is none other than Agrippa's father. Using Caesar's last words: "You too, Brutus?" as his primary clue, Octavianus sets off on a quest to uncover the truth with the aid of his mentor, Pansa.
- Antonius - Caesar's loyal underling, Antonius vows to strive for the good of Rome, following the assassination. It turns out he was behind the plot to kill Caesar.
- Cicero - A superior statesman and eloquent speaker, Cicero is a born leader and a natural choice to head the Senate. It is he who formally denounces Vipsanius as a criminal.
- Vipsanius - A close trusted associate of Caesar, Vipsanius is the father of Agrippa. Falsely accused of Caesar's brutal murder, he is incarcerated in the Syracuse prison.
- Barca - The general of a large force of barbarians in Germania, Barca loses his battle with Agrippa and is transported to Rome as a captive.
- Pansa - Formerly Caesar's chief intelligence officer, Pansa is now retired and leads a quiet life. He has a mysterious connection with Octavianus' family and is happy to aid him.
- Maecenas - Secretary of Antonius and loyal servant of Caesar, it is Maecenas who suggests that a gladiatorial tournament be held, and that the winner should play executioner. Octavianus soon views Cassius' murder scene and witnesses firsthand the hiding of the body.
- Decius - A general in the Republic's army, Decius led Rome's brave armies to victory after victory for the great Caesar. He loves nothing more than the sight and smell of blood. He quite visibly takes pleasure in the public execution of Agrippa's falsely accused mother. Always accompanied by members of the Valcross stable, he often participates in gladiatorial games himself.
- Claudia - A popular fighter, Claudia calls Sextus her brother. After witnessing Agrippa's prowess firsthand, she encourages him to join her gladiator stable. Sold to Rome in the slave trade as a mere child, she was taken in by Sextus. Unable to heal the scars of her past, she holds a simmering hatred of Rome in her heart.
- Sextus - A promoter who manages a stable of gladiators outside of Rome, Sextus is known for his easygoing attitude which has earned him the respect of the gladiators in his care. He receives an assassination request from a pair of mysterious twins known as Iris and Charmian. Ten years earlier, Sextus purchased Claudia from a slave trader and brought her up as he would his own younger sister.
- Marcus - Also known as Marcus Brutus, Marcus is employed as a justice along with Cassius. He views Cicero as his mentor. His relationship with Cassius ends on bad terms following a quarrel, and Cassius' dead body is discovered soon after. This is followed by Marcus' own sudden disappearance.
- Cassius - Employed as a justice with Marcus, Cassius often partook of disquieting, secret exchanges of information with his co-worker over drinks. Soon after parting on bad terms with Marcus, Cassius' body is found and taken away by Maecenas and his men.
- Iris and Charmian - Iris and Charmian are the female twins who have requested the assassination of a certain person (probably Cleopatra). They pass their request to Sextus.
- Arcanus - A Valcross stable archer that battles Agrippa in a fight to the death.
- Narclastese- Valcross stable chariot racer. Characterized by his flamboyant dressing and attitude. After he fails to win against Agrippa he meets his end by Decius' hand, as punishment for further dishonor of the good Valcross name.
The premise and story of the game revolves around the murder of Julius Caesar, and its aftermath. The story is progressed through Octavianus' portions in the game.
After the death of Caesar, Antonius ascends to the throne as the new Emperor. Promising to lead Rome with the dignity and brilliance the former Caesar did, he is cheered and loved by everyone.
General Agrippa - after a successful raid against a Barbarian outpost - is told that Julius Caesar has been murdered. Shocked, he returns to the Foro Romano, where he is told that his father, Vipsanius, has been framed for the murder. To make matters worse, his mother has been condemned to death. Agrippa cannot accept this, and decides to free his mother by killing her guards. Before they can escape the city, however, she is killed by General Decius, who then defeats Agrippa in battle. Before he is killed, however, Agrippa is rescued by Claudia, a female gladiator. After they are safely away, she tells him that a tournament is to be held to determine Vipsanius' executioner, and that Decius is to compete in the final round. Knowing he cannot return to Rome a free man, he decides to become a gladiator and compete in the tournament.
Meanwhile, Octavianus decides to look into the matter himself. Through various endeavors into the Roman Senate, he finds out that indeed, Vipsanius is not the true murderer of Caesar. The dying Cicero informs Octavianus that a group of conspirators are the ones responsible for the murder. One by one, select Roman Senators are murdered, leading Octavianus to believe that someone does not want them to talk.
As Agrippa continues to advance in rounds, he learns that his owner, Sextus, has more than his share of secrets. Towards the end of the game, he accepts a proposal from the Egyptian twins Iris and Charmian, whose mistress is hinted to be Cleopatra, to assassinate someone of great importance. He then disappears for a time, only to reappear an assassin. His father, Pompeius, was defeated in battle by Caesar's troops, and Sextus wants revenge. Since Octavianus is Caesar's immediate family, and thus true heir to the throne, Sextus goes after him, but is stopped by Claudia. Octavianus is arrested for his snooping by Maecenas, Antonius's secretary, soon after.
During the final, decisive match between Agrippa and Decius, Maecenas reveals to the masses of Rome that Caesar was not killed. Instead, his assassins murdered a double. They were employed by none other than Antonius, who found out that he was not really Caesar's heir. In the ensuing argument, it is revealed to the public that Decius is the Caesar double's true killer. The tournament was articulated by Maecenas in order to reveal the conspiracy and Caesar's true heir to a wide audience. Outraged, Antonius orders Decius to murder Maecenas, Vipsanius, and Octavianus, but Agrippa steps in, and defeats Decius for the final time. Decius dies and he saw his death as a dishonorable death by a gladiator .
Antonius decides to fight Agrippa himself, but loses. As guards take him away, Sextus and his army climb the walls of the Colosseum and demand Antonius. Agrippa rejoins the Roman army in taking back the streets from Sextus' army, joined by Claudia soon after. As they meet Sextus at the docks, Claudia pleads that he not fight Agrippa, but is knocked away. She regains consciousness just as Agrippa stabs Sextus. Agrippa himself begs him to give up, but before Sextus can respond, Antonius' ship fires at a lighthouse behind Sextus. As it begins to fall over, he begins to reminisce about his early days with Claudia. He calls out to her one more time before the lighthouse falls and crushes him. Agrippa and Claudia mourn his death, and Agrippa decides to go after Antonius along with the Roman navy.
After reaching the flagship, Agrippa battles Antonius, and defeats him. As he and Octavianus return to Rome, they are given a hero's welcome. The two find Claudia mourning Sextus on a cliff overlooking the docks. She tells them that she is leaving Rome to travel the world. As she leaves, Agrippa asks her to come back and visit some day. She smiles at him, turns away, and walks off. Octavianus vows to seek the Pax Romana, and Agrippa vows to help him any way he can.
There is a final game revelation after the end credits. Iris and Charmian ask each other if they're ready, and state that it's time to tell their mistress that they've reached the end of the beginning.
- The final stage is based on the historical Battle of Actium, where the naval fleets of Octavianus led by Marcus Vipsanius Agrippa and Marcus Antonius (Mark Antony) faced in battle in the year 31 B.C. Antonius committed suicide after the defeat, similar to how he fell off his ship once you defeat him. Word got to his wife, Cleopatra about his death and she committed suicide as well.
- Keiji Inafune liked the game so much that he planned to have a sequel made. Instead, because of poor sales in America, it was changed into Dead Rising.