The 1P Game (also known as 1 Player Game and 1P Game Mode) is the only single-player campaign mode available to play in Super Smash Bros. In the mode, players progress through a series of 11 matches (interrupted by a bonus stage after every three matches), culminating in a final battle with the game's boss, Master Hand. 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. There are fourteen stages including bonus stages in this mode and players may choose their character, the difficulty, and number of lives before the playthrough.
The 1P Game did not return proper for Super Smash Bros. Melee. The aspect of fighting a series of opponents en route to Master Hand, however, was included in the redone Classic Mode, though this mode featured a more streamlined structure, alongside other improvements. Additionally, some fights in the 1P Game reappeared as challenges in the new Adventure Mode, such as the fight against the Yoshi Team and Giant Donkey Kong. In Super Smash Bros. Ultimate, Jigglypuff's Classic Mode route may be a reference to this mode, since it consists only of characters and stages from Smash 64.
Stage 1: Link
Stage 2: Yoshi Team
The second stage takes place on Yoshi's Island and pits the player against the Yoshi Team, comprised of 18 lightweight Yoshis. 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.
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
Stage 4: Mario Bros.
The fourth stage takes place at Peach's Castle and pits the player against the Mario Bros., comprised of Mario and Luigi. In this stage, the player is accompanied by one, randomized ally. Curiously, Luigi will still appear even if the player has not unlocked him.
Stage 5: Pikachu
Stage 6: Giant Donkey Kong
Stage 7: Kirby Team
The seventh stage takes place in Dream Land and pits the player against the Kirby Team, comprised of 8 lightweight Kirbys. Each of the eight Kirbys sport a unique hat (with the exception of the final one, which will be 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. Except for the average and unlockable character Kirbies, 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), he will be awarded the 25,000-point bonus Kirby Ranks.
Stage 8: Samus
Stage 9: Metal Mario
Stage 10: Fighting Polygon Team
Stage 11: Master Hand (Final Stage)
The final stage takes place at the Final Destination and pits the player against Master Hand. 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 lowering the opponent's stamina to 0 HP. Master Hand on all difficulties has 300 HP.
These stages are optional to complete. The player has one stock for each of the stage and if time runs out or the player gets KO'd, the match will end in failure and will move on to the next stage.
Bonus Stage 1: Break the Targets
The first bonus stage is Break the Targets and takes place after stage 3, the match against Fox. It challenges the player to seek and destroy the ten targets placed throughout the stage within a 2-minute time limit.
Bonus Stage 2: Board the Platforms
The second bonus stage is Board the Platforms and takes place after stage 6, the match against Giant DK. 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. When a platform has been boarded, the otherwise red light it emits will become blue.
Bonus Stage 3: Race to the Finish
The third and final bonus stage is Race to the Finish and takes place after stage 9, the match against Metal Mario. 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, in this one, the player has only one minute to complete the stage, instead of two.
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!". All such screens are entirely original images made solely 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!" in place if the player manages to score at least 1 million points by the end of the game.
The congratulations screens are present only in the American and European versions of the game, and not in the Japanese version.
- Clearing 'Break the Targets' with all eight original characters will have Luigi challenge the player where defeating him will unlock him.
- Clearing the 1P Game without any continues on any difficulty will have Jigglypuff challenge the player where defeating it will unlock it.
- Clearing the 1P Game in less than twenty minutes and no continues will have Captain Falcon challenge the player where defeating him will unlock him.
- Clearing the 1P Game with 3 lives and no continues on the Normal difficulty will have Ness challenge the player where defeating him will unlock him.
- Clearing the 1P Game and using all eight of the original characters and playing on all the default stages will reward the player with the Mushroom Kingdom stage.
- 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.