Spoiler alert: The following section contains plot-specific details.(Skip Section)
Hyness' prayer opened a path from another dimension...to new dimensions untold. What possibilities await? Will you be a Dream Friend? Will you face even greater evil? Collect hearts and explore new worlds. The light of hope is yours to create.”
Heroes in Another Dimension is a sub-game in Kirby Star Allies. It was added to the game as a part of the 4.0.0 Update on November 30, 2018.
Hyness' constant prayers after the defeat of Void Termina and the destruction of the Jamba Heart have lead the Jambandra Base to the edge of Another Dimension. Kirby arrives at The Divine Terminus to find it empty, aside from a dimensional rift that has opened up. Kirby enters this dimensional rift that leads to Another Dimension, and recruits Friends and Dream Friends alike in order to obtain Friend Hearts and the Heart Spears being guarded by parallel versions of Kirby's past foes. As each parallel boss is defeated, the Jambandra Base approaches Another Dimension, with The Divine Terminus becoming more corrupt as it gets closer. After defeating all four parallel bosses to obtain all four Heart Spears, one last dimensional rift opens, leading to Hyness' location. Kirby and friends come across a new Jamba Heart. Using the power of the Heart Spears, the Jamba Heart is pierced and shattered to pieces, revealing a now Corrupt Hyness. After Hyness is defeated yet again, The Three Mage-Sisters arrive. Upset about the defeat of their master, they turn to face Kirby, fighting as a team.
Similarly to early games in the franchise, the ending changes depending on how many of the mode's collectibles were obtained, Friend Hearts in this case; however, the player only needs to obtain 100 for the good ending, not all 120. If less than 100 are obtained, after the victory dance, Kirby and Friends will leave. The camera will slightly zoom in on the fallen mages as dark auras begin to surround them and an ominous jingle, similar to the one that plays in the Kirby 64: The Crystal Shards bad ending, plays, signaling it to be a bad ending.
If more than 100 Friend Hearts are obtained, Kirby uses the accumulated Friend Hearts to return The Three Mage-Sisters back to their former selves, to which they use their powers to take The Divine Terminus away from Another Dimension. A Warp Star floats down for Kirby and co. to ride home with. As they fly away, the Warp Star creates a small explosion of hearts; one of the hearts lands on Hyness, bringing him back to normal, to the Mage-Sisters' relief. If all 120 are collected, artwork is shown after the credits that the villains and Kirby have finally resolved their conflict.
In this mode, Kirby and co. navigate through Another Dimension, with Friend Hearts being the main collectible; there are 30 Friend Hearts in each of the main four dimensions, for a total of 120. Various puzzles that utilize Friend Abilities are present in Another Dimension. Hero Doors give Kirby a specific Copy Ability or change him into a particular Dream Friend. Player 1 uses every Dream Friend throughout the mode. In addition to exploring new levels, there are also newer, more difficult bosses. After beating this mode, the player will unlock a new difficulty in The Ultimate Choice: Soul Melter EX.