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 and number of lives before the playthrough. The 1P Game was redone into Classic Mode in Super Smash Bros. Melee and featured a number of changes, among them the removal of the fixed match order.
 Match stages
 Stage 1
 Stage 2
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. Strangely though, the clouds at the sides of the stage are missing. However, using a Gameshark to use the Debug Menu can allow the player to access this version of Yoshi's Island with the clouds missing. Defeating the Yoshis in the order that they appear gives the player the Yoshi Rainbow bonus, worth 50,000 points.
 Stage 3
 Stage 4
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
 Stage 6
 Stage 7
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 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
 Stage 9
 Stage 10
 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 out the opponent, but only by lowering the opponent's stamina to 0HP.
 Bonus stages
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
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
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
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.
 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!". 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 a least 1 million points by the end of the game.
These screens are present only in the American and European versions of the game; the Japanese version does not have these screens.