The Elder Scrolls IV: Oblivion

Gameplay
Oblivion is a fantasy-based role-playing adventure game and an example of open-ended or sandbox gameplay. The main quest may be delayed or completely ignored as the player explores the expansive game world, following side quests, interacting with NPCs, and developing a character according to their taste. The player is free to go anywhere inside the land of Cyrodiil at any time while playing the game, and even after completing the main quest storyline the game never ends, allowing the player to build their character in whatever way they want, with no restrictions on skills or equipment. The game contains many enemies for the player to fight, including monsters and animals. Many enemies, quests, and treasures are "leveled", or become increasingly difficult, as the player gains levels. The player, however, has the option of adjusting the difficulty level.

The fast-travel system found in Arena and Daggerfall, but left out of Morrowind, returned in Oblivion. In Oblivion, if a player visits a location, it appears as an icon on their map. The icon may then be clicked to visit that location, with time elapsing in the interim. Oblivion also introduced ridable horses while removing Morrowind's transportation options, such as Mages' Guild teleporters, silt striders and teleporting spells. The game also removed all levitation spells and items, as the cities in Oblivion are separate cells from the rest of the world and thus must be entered into, and exited from, the town gate to avoid glitches. Unlike those of Morrowind, Oblivion ' s non-player characters may enter and exit areas at will, and will do so quite often, following the Radiant AI's commands.

One major focus during Oblivion ' s development was correcting Morrowind ' s imbalance between stealth, combat and magic skill sets. The skills system is similar to Morrowind ' s, though the number of skills is decreased, with the medium armor and unarmored skill removed altogether, and the short blade and long blade skills condensed into a single blade skill. The game also introduced "mastery levels," which give skill-specific bonuses when the player reaches a certain level in that skill. The combat system was also revamped, with the addition of "power attacks", generally given by mastery levels, and the removal of the separate styles of melee attacks present in Morrowind. Ranged attacks were also changed, so that the determination of a hit is based solely on whether the arrow struck the target in-game, rather than the character's skill level. Spears, throwing weapons, and crossbows were removed as well, while staffs no longer counted as weapons, but are only used for casting spells. The choice came from a desire to focus all development efforts in ranged weapons on bows specifically, to "get the feel of those as close to perfect as possible", as perfect as the Havok physics engine allowed the team to do. Morrowind ' s passive Block skill became an active feature in Oblivion, activated by a button press. When, in the new system, an enemy is successfully blocked, they now recoil, offering an opening for attack.

Plot
Although it is set after the previous Elder Scrolls games chronologically, the game is not a direct sequel to The Elder Scrolls III: Morrowind or any other game. Oblivion begins with the arrival of Emperor Uriel Septim VII (voiced by Patrick Stewart), accompanied by a troupe of Blade bodyguards, at the palace prison, seeking to flee from a group of assassins—later revealed to be members of the Mythic Dawn—through a secret underground exit. By chance, the exit is located in the cell occupied by the protagonist. The Emperor frees the player, and sets off through exit into the catacombs as the protagonist follows. At the end of the catacombs, the group is ambushed, and quickly overwhelmed by assassins, which results in the protagonist taking on the task of guarding the Emperor while the surviving bodyguards engage the enemy. While awaiting the result, Uriel entrusts the protagonist with the Amulet of Kings, a special amulet that can only be worn by those of the Septim bloodline, and orders the player to take it to a man named Jauffre. Immediately afterwards, an assassin ambushes and kills the emperor before he is, in turn, defeated. The sole surviving guard, Baurus, questions the protagonist, and explains that Jauffre is the Grandmaster of the Blades, and can be found at Weynon Priory.

As the game progresses, it is revealed that the Emperor's death has allowed multiple gates to Oblivion to open, and a Daedric invasion is to begin as a result. The only way to close down the gates permanently is to find someone of the Septim bloodline to retake the throne and re-light the Dragonfires in the Imperial City. Fortunately, it is also revealed that there is indeed still an heir to the Septim throne: an illegitimate son named Martin Septim (voiced by Sean Bean), who resides in Kvatch. However, the Daedra have Kvatch under siege and the protagonist has to venture into the Planes of Oblivion and close down the gate. After having closed the gate, the protagonist arrives at the Kvatch chapel and persuades Martin to join him to travel back to Weynon Priory.

Upon arriving, the player finds that Weynon Priory is being raided by the Mythic Dawn and the Amulet of Kings has been stolen. Recovering from the attack, Jauffre orders the protagonist to escort himself and Martin to Cloud Ruler Temple, the stronghold of the Blades in the Jerall Mountains. At Cloud Ruler Temple, Martin is recognized as the Emperor and is given command of the Blades, and the protagonist is sent off in search of the Amulet. After some investigating, the protagonist arrives at the Shrine of Mehrunes Dagon, a Daedric cult lair run by the Mythic Dawn, believing the Amulet to be held there. The Mythic Dawn's leader Mankar Camoran (voiced by Terrence Stamp) escapes to his Paradise through a portal using a mystical book called the Mysterium Xarxes. The protagonist recovers this book and returns it to Martin, who deduces that the only way to recover the Amulet is to follow Camoran, and create a portal to the paradise as well. A "collect-the-pieces" plot begins, as the player must recover three key items that are necessary to recreate the portal. Having acquired all three items, Martin reveals a final item that needs to be used in order to create the portal, a Great Sigil Stone used in a Great Gate to the Planes of Oblivion, similar to the one that devastated Kvatch. Martin and Jauffre hatch a plan that involves allowing Bruma to be attacked by the Daedra so that a Great Gate can be opened. The protagonist then must venture into the gate and obtain the Great Sigil Stone. Arriving on the battlefield of Bruma, Martin gives a moving speech before charging into battle against the Daedra. Many men are lost, but a Great Gate is finally opened. The protagonist enters and recovers the stone.

Upon returning to the Temple, a portal is created and the protagonist ventures through, arriving at Camoran's paradise. After fighting through Camoran's men, the protagonist confronts him in his throne room, and slays him in battle. Upon his death, the protagonist takes the Amulet from Camoran's neck, and sees Paradise evaporate around him. The protagonist returns the Amulet to Martin, and the Blades travel to the Imperial City to re-light the Dragonfires, ending the Daedric invasion. However, the Daedra begin a desperate assault of their own and overrun the Imperial City. The protagonist and Martin fight their way to the Temple of the One, in the Imperial City Temple District, to find that a 200-foot tall beast is wreaking havoc in the city, revealed to be the Daedric Lord Mehrunes Dagon himself. Martin fights his way into the Temple, and shatters the Amulet of Kings to merge himself with the spirit of Akatosh, the Dragon-God of Time, becoming his Avatar. He defeats Dagon in one final confrontation. The Amulet of Kings is destroyed, Martin disappears, the gates of Oblivion are shut forever, and the throne of the Empire again lies empty. A final monologue by Martin, describes this in an optimistic light, claiming that the future of Tamriel is now in the protagonist's hand. After the battle, Lord Chancellor Ocato of the Elder Council proclaims the protagonist Champion of Cyrodiil.