1P Game

The 1P Game (also known as 1 Player Game, 1P Game Mode, or sometimes Classic Mode) is the only single-player campaign mode available to play in Super Smash Bros. In the mode, players progress through a series of eleven stages, culminating in a final battle with the game's boss,. In addition, there are three optional bonus stages–one after every third match–where the player has one stock to complete the stage before time runs out. Clearing each stage, including the bonus stages, gives the player bonus points that contribute to a total score. The mode has a static nature in which the player faces the same characters on the same stages in a fixed order during each playthrough. Players may choose their character, the difficulty, and number of lives before the playthrough.

The 1P Game did not return proper in Super Smash Bros. Melee. In Melee, the aspect of fighting a series of opponents en route to Master Hand (and depending on the difficulty, Crazy Hand) was instead included in the redone. However, this mode featured randomized opponents and a more streamlined structure, alongside other improvements. Additionally, some fights from the 1P Game reappeared as opponent characters in the new 1 player mode Adventure in Melee (including the Yoshi Team, Giant Donkey Kong, the Kirby Team, and Metal Mario). In this regard, the Adventure mode can be seen as an enhanced remake of the 1P Game. In Super Smash Bros. Ultimate, 's route is a reference to this mode, since it consists only of characters and stages from Smash 64, even starting with  in his tunic alternate costume and fighting Giant Donkey Kong.

Each stage, excluding bonus stages, has 5 minutes for the player to KO their opponent(s). However, the player is able to disable this time limit, but doing so prevents the player from receiving time bonuses.

Stage 1: Link
The first stage takes place at Hyrule Castle and pits the player against. Having Link KO'd by a Tornado stage hazard will net the player the Tornado Clear bonus, worth 3,000 points.

Stage 2: Yoshi Team
The second stage takes place on and pits the player against 18 lightweight s. The Yoshis rarely attack and as they are lightweights, they are exceptionally weak and can be knocked out by almost any attack; sometimes they may even fall from the stage without any conflict from the player. Defeating the Yoshis in the order that they appear gives the player the Yoshi Rainbow bonus, worth 50,000 points (15,000 points in the Japanese version).

This stage takes place on a version of Yoshi's Island without the clouds off to the side of the stage; while normally inaccessible, it is possible to access the stage via hacking.

Stage 3: Fox
The third stage takes place in Sector Z and pits the player against. Having Fox KO'd by an Arwing stage hazard will net the player the ARWING Clear bonus, worth 4,000 points (3,000 points in the Japanese version).

Bonus Stage 1: Break the Targets
The first bonus stage is Break the Targets. It challenges the player to seek and smash ten targets placed throughout the stage within a 2-minute time limit.

Stage 4: Mario Bros.
The fourth stage takes place at Peach's Castle and pits the player against the Mario Bros., consisting of and. In this stage, the player is accompanied by one, randomized ally. Curiously, Luigi will still appear even if the player has not unlocked him. Knocking out one Mario brother before hitting the other will earn the player the Bros. Calamity bonus, worth 25,000 points (12,000 points in the Japanese version). Defeating both Mario Bros. without the teammate being KO'd nets the Good Friend bonus, worth 8,000 points (5,000 points in the Japanese version). Defeating them without the teammate being damaged at all earns the True Friend bonus, worth 25,000 points (30,000 points in the Japanese version).

Stage 5: Pikachu
The fifth stage takes place in Saffron City and pits the player against.

Stage 6: Giant Donkey Kong
The sixth stage takes place in Congo Jungle and pits the player against Giant Donkey Kong. In this stage, the player is accompanied by two randomly selected allies. Defeating Giant Donkey Kong without either teammate being KO'd nets the DK Defender bonus, worth 10,000 points (7,000 points in the Japanese version). Defeating him without either teammate being damaged at all earns the DK Perfect bonus, worth 50,000 points.

Bonus Stage 2: Board the Platforms
The second bonus stage is Board the Platforms. It challenges the player to seek and step on the surfaces of the ten platforms placed throughout the stage within a 2-minute time limit.

Stage 7: Kirby Team
The seventh stage takes place in and pits the player against 8 lightweight s. Each of the eight Kirbys sport a unique hat (with the exception of the final one, which will be either normal Kirby, or one of the four unlockable characters after they've been unlocked) corresponding to each of the eight starter characters in the game. There are always two Kirbys at a time for the player to face. Except for the average and unlockable character Kirbys, they all appear in the selection screen order of the respective character whose power they copied. Keeping this in mind, if the player manages to defeat them in the right order (Mario, DK, Link, Samus, Yoshi, Fox, Pikachu, regular/random unlockable), they will be awarded the Kirby Ranks bonus, worth 25,000 points (12,000 points in the Japanese version).

Stage 8: Samus
The eighth stage takes place on Planet Zebes and pits the player against. Having Samus KO'd by the rising acid stage hazard will net the player the Acid Clear bonus, worth 1,500 points (1,000 points in the Japanese version).

Stage 9: Metal Mario
The ninth stage takes place at Meta Crystal and pits the player against Metal Mario.

Bonus Stage 3: Race to the Finish
The third and final bonus stage is. It challenges the player to descend five floors and reach the exit, while avoiding explosives, bumpers, and some of the Fighting Polygon Team. Unlike the other bonus stages, the player has only one minute to complete the stage.

Stage 10: Fighting Polygon Team
The tenth stage takes place on Duel Zone and pits the player against the Fighting Polygon Team, consisting of 30 lightweight Fighting Polygons, weak copies of the twelve playable characters.

Stage 11: Master Hand (Final Stage)
The final stage takes place at the and pits the player against. This stage stands out from most others in the game, as it can not be cleared by knocking the opponent out past the blast line, but only by reducing the opponent's stamina to 0 HP. Master Hand on all difficulties has 300 HP.

Congratulations screen
Upon clearing the 1P Game, the game gives the player a small reward: a static image featuring the character in a specific scene along with the announcer saying "Congratulations!". Most of these screens are entirely original images made for the game; the sole exception is Captain Falcon's, which was an unlockable title screen for F-Zero X. The announcer will also exclaim "Incredible!" if the player manages to score at least 1 million points and no miss 11 times by the end of the game.

The congratulations screens are present only in the American, PAL, and Chinese versions of the game, and not in the Japanese version.

Unlockables

 * Clearing the 1P Game in 20 minutes or less will unlock.
 * Clearing the 1P Game on any difficulty will unlock.
 * Clearing Break the Targets with all eight original characters will unlock.
 * Clearing the 1P Game with 3 lives or less and no continues on the Normal difficulty or higher will unlock.
 * Clearing the 1P Game, playing as all eight starter characters, and playing on all the default stages will unlock.

Trivia

 * While the points counter can theoretically feature values above ten million due to having eight possible digits, only hacks that force the counter to its maximum value can cause it to feature such numbers.
 * Luigi is the only unlockable character that appears as an opponent character on 1P Game Mode (as he appears in Stage 4). Captain Falcon, Jigglypuff, and Ness (the other three of the four unlockable characters) can appear as ally characters in Stages 4 and 6, but none of them will appear as opponent characters.
 * Allies in Stages 4 and 6 will never be the same character as the player (i.e. if the player is Link then the ally characters cannot be Link). Also the allies cannot be the same character as each other (i.e. 2 Nesses) in the stage 6 fight against Giant DK. Allies will always use their default costume (including DK against Giant DK) except for Luigi in the stage 4 fight against Mario Bros. in which case he will use his first alternate costume instead. Mario will never be selected as an ally in stage 4 against Mario Bros.
 * Within a similar mode via Ultimate's Classic Mode, Jigglypuff and Bowser are the only characters who face a mini-boss from originating from 1P Game. Jigglypuff faces Giant Donkey Kong while Bowser fights Metal Mario upon defeating a default Mario.
 * Both mini-bosses serve as both characters' final rounds in Classic Mode each.