Bastion is an action role-playing game with a level structure. The player character, "the Kid", moves through floating, fantasy-themed environments that form paths as the player approaches the edge. Levels consist of a single plane, and are viewed isometrically. They are filled with enemies of various types, which attempt to harm the Kid. The Kid carries two weapons, which may be selected from the choices available to the player at specific locations called arsenals. The Kid also has the ability to perform a special attack. Weapons and special attacks must be acquired before they can be used. There are a limited number of special attacks that the player can perform at any time, represented by "black tonics" that can be found in the levels or dropped from enemies. Special attacks may be used a total of three times. This maximum number of uses can be increased in the Distillery. The Kid's health is represented by a health bar, which can be replenished with "health tonics". Like black tonics, the Kid can only carry a certain number of health tonics at a time, and can replenish them by finding more in the levels.
Levels contain many different environment types, including cities, forests, and bogs. At the end of most levels, the player collects an item called a core or a shard; occasionally, the level begins to disintegrate once the Kid takes the item, forcing him to hastily retreat. As the player progresses through the levels, a voice narrates their actions. This narration gives scripted plot information as well as dynamic comments, such as on the player's skill with a weapon or performance while fighting enemies.
Between levels, the Kid visits the Bastion, where the player can use fragments—the game's form of currency—that they have accrued to buy materials and upgrade weapons. With each core the player collects, they can add one of six structures to the Bastion, such as a shrine, an armory, or a distillery, and each shard allows the player to expand a structure. Each structure serves a different purpose; for example, the distillery lets the player select upgrades, and the shrine allows the player to choose idols of the gods to invoke, causing the enemies to become stronger and giving the player increased experience points and currency. Experience points are used to determine the Kid's ability level; higher values give the player more health and increase the number of upgrades they can select.
Whenever the player leaves the Bastion, they can choose between one or two regular levels to play. In addition to these levels, however, the Kid can engage in challenge courses designed to test the player's skills with the weapons the player has found. They are called Proving Grounds. The challenges differ depending on the weapon, such as destroying a certain number of objects within a given time or breaking targets in the fewest shots possible. According to the player's score, different tiers of prizes are awarded. Additionally, the Kid can fight waves of enemies while the narrator tells a character's backstory by journeying to "Who Knows Where" from the Bastion. The back story battles occur during 'Memories.' The player earns fragments and experience for each completed wave. After the game is completed, the player can choose to begin a "new game+" mode, where the player replays through the game while keeping the experience points, fragments, and weapons that they have gained. This mode also offers more options in the buildings, as well as two more journeys to "Who Knows Where".
Plot
The game takes place in the aftermath of the Calamity, a catastrophic event that suddenly fractured the city of Caelondia (/seɪˈlɒndiə/) as well as the surrounding areas of the game's world into many floating pieces, disrupting its ecology and reducing most of its people to ash. Players take control of the Kid, a silent protagonist who awakens on one of the few remaining pieces of the old world and sets off for the eponymous Bastion, where everyone was supposed to go in troubled times. The only survivor he meets there is an elderly man named Rucks, the game's narrator, who instructs him to collect the Cores that once powered Caelondia. A device in the Bastion can use the power of the crystalline Cores to create landmasses and structures, as well as enable the Kid to travel farther afield via "skyways" that propel him through the air.
During his quest, the Kid meets two more survivors: Zulf, an ambassador from the Ura, underground-dwelling people with whom Caelondia was once at war; and Zia, an Ura girl who was raised in Caelondia. Both of them return to the Bastion, but upon reading a journal that the Kid discovers, Zulf intentionally damages parts of the Bastion's central device (the monument) and returns to Ura territory. The Kid learns that the journal belonged to Zia's father, Venn, who had worked for the Caelondians. He had helped Caelondian scientists ("Mancers") build a weapon intended to destroy the Ura completely to prevent another war. Venn rigged the weapon to backfire, so that when he was finally forced to trigger it, the resulting Calamity destroyed most of Caelondia as well.
To repair Zulf's damage to the Bastion, the Kid starts collecting Shards, a lesser form of Cores. As he obtains the penultimate shard needed, the Ura attack the Bastion, damaging it and abducting Zia. In the next seven days, The Kid engages in sporadic skirmishes in Ura territory. When he finally blasts through an Ura outpost and meets Zia, she tells him that she had left with the Ura voluntarily to find out their intentions; Rucks had previously told Zia that the Bastion had the ability to somehow fix the Calamity. The Kid travels to the once-underground Ura homeland to retrieve the last shard. There, he discovers Zulf being attacked by his own people: the battle with the Kid has devastated the Ura forces, and they blame Zulf for bringing the Kid to their home. The Kid can choose to drop his weapon to help Zulf or leave him. If he leaves Zulf behind, the Kid destroys the remnants of the Ura and escapes through a skyway. If he chooses to carry Zulf, Ura archers initially open fire on them but ultimately cease fire and watch silently as the Kid and Zulf take the skyway back to the Bastion.
After the Kid returns and recovers, Rucks gives him another choice: He can have the Bastion rewind time to before the Calamity in the hopes of preventing it, or use it to evacuate the survivors and move on to somewhere safe. Rucks is unsure if there is any way to prevent the Calamity from reoccurring if the time is rewound, as there was no way to test the process. The game ends either way, showing images of the characters (with the inclusion of Zulf if the player chose to rescue him) flying away or of their lives before the Calamity along with the credits. In the New Game+ mode, which is unlocked after beating the game once, it is hinted that restoring the world didn't prevent the Calamity.
