Super Smash Bros. for Nintendo 3DS is the fourth entry in Nintendo's crossover fighting franchise, featuring dozens of characters from across Nintendo's catalog, along with a few special guests. The basic formula is unchanged since the previous title: up to four characters, controlled by either human players or the computer, duke it out in a side-scrolling arena. As characters take damage, they are sent flying further by attacks, and if they fly -- or fall -- out of the arena, then they're out!

Most of the fighters from previous entries have returned, along with numerous newcomers, including Mega Man, Pac-Man, Little Mac (Punch-Out), Shulk (Xenoblade Chronicles), Palutena (Kid Icarus), Villager (Animal Crossing), and numerous others for a total of more than three dozen playable characters. It is also possible to design a custom Mii-style fighter using parts and abilities unlocked throughout the game; this character can also be transferred for use in Super Smash Bros. for Wii U.

The game includes standard 2-to-4-player battle modes, including both time and stock matches, playable via either local wi-fi or internet play. New in this entry is the Smash Run mode, where each player must defeat enemies in a sprawling world map to collect upgrade items to boost their character's abilities. When the time is up, players then fight against each other with their upgraded characters. Returning from previous entries is the All Star mode, where the player must defeat all other characters in the game in order, with only limited healing items available. The trophy collection system introduced in Melee also returns, giving players a glimpse at classic and modern Nintendo characters and other objects in full 3D.