World of Trophies
The World of Trophies, also known simply as This World (この世界) according to the Smash Bros. DOJO!! website and some trophy descriptions, is the setting in which The Subspace Emissary takes place. According to Master Hand's trophy description, he is the ruler of this realm.
The World of Trophies is a large land mass with a very diverse geography that includes grasslands, a large lake, temperate and tropical forests, wetlands, badlands, and a snowy mountain. Interestingly, there are remnants of civilization strewn about the World of Trophies. This is evident with the existence of a dilapidated zoo, a large castle, and an area consisting of ancient ruins.
The World of Trophies is neighbored by a vast ocean and two locations that are located in the sky: a floating island known as the Isle of the Ancients, and a location based on and named after Skyworld.
Initially, the opening movies of Super Smash Bros. and Super Smash Bros. Melee merely showed playable characters as toy/trophy versions of themselves. Prior to the release of Super Smash Bros. Brawl, Masahiro Sakurai developed this quirk into an integral aspect within the Super Smash Bros. universe's lore. According to Sakurai, playable characters live on the World of Trophies and fight each other in a variety of battles. Upon defeat, a character is turned into a trophy, a process that is akin to death. However, a defeated character can be revived in two ways: either by simply touching their Trophy Stand, or by equipping them with a special brooch. As shown in Brawl's Adventure Mode, The Subspace Emissary, non-playable characters can also be turned into trophies upon being hit with a Trophy Stand, and NPCs created from Shadow Bugs can even be outright destroyed.
Although fighting is the primary purpose among the playable characters within the Super Smash Bros. series, Sakurai explains that it also serves as a form of bonding between them, regardless of which universe they hail from. This is first shown in the fight between Mario and Kirby at the Midair Stadium, where the winner of the fight revives the loser and then cordially shake hands afterward. These bonds are further developed in response to the threat of the Subspace Army, as the playable characters collectively unite to stop the Subspace Army from destroying the one home that they collectively share.
Despite the remnants of civilization located around the World of Trophies, there may be some active form of civilization aside from the trophies, as evident by the crowd in attendance at the Midair Stadium. While the true depth of the World of Trophies' civilization is ambiguous, it nevertheless has a ruler: the aptly named Master Hand, who is the embodiment of creation within the Super Smash Bros. universe. Incidentally, Skyworld is ruled by Palutena like in her and Pit's home universe, whereas the Isle of the Ancients was formerly ruled by the Master Robot prior to the Subspace Army's invasion. Although the playable characters were successful in stopping the Subspace Army and its leader, Tabuu, from fully capturing the World of Trophies within Subspace, this came at a heavy cost: R.O.B., who was the Master Robot/Ancient Minister, became the sole survivor of his species, and the Isle of the Ancients was effectively destroyed after being engulfed in a plethora of Subspace Bomb explosions.
Although the World of Trophies is not directly featured in Super Smash Bros. 4, it and the events of The Subspace Emissary are nevertheless referenced. In Super Smash Bros. for Wii U, R.O.B.'s status as the only remaining member of his species is referenced by his NTSC Boxing Ring title "The Last of His Kind". In addition, Palutena's Guidance regarding Mario and Mr. Game & Watch directly mention Pit's alliance with Mario early on in The Subspace Emissary, and Mr. Game & Watch's ability to generate Shadow Bugs, respectively. In Super Smash Bros. for Nintendo 3DS, Generators, Glices, Glires, Glunders, Mites, Poppants, and Roturrets appear in Smash Run, while their respective trophies directly mention the Subspace Army.
Although it is never explicitly stated, it can be assumed that Super Smash Bros. Ultimate's Adventure Mode, World of Light, takes place at least partially in the World of Trophies, making it a pseudo-sequel to The Subspace Emissary. This is most evident in the opening cutscene, where the initial fight against Galeem seemingly takes place on the same cliffside that formerly showed the Isle of the Ancients on the horizon as shown during the final Subspace Emissary cutscene. It should be noted that the world is destroyed and rebuilt following this cutscene, which explains why the in-game map is completely different to that of the one featured in The Subspace Emissary.
The Subspace Army is also directly referenced in a few ways. Tabuu, Duon, and the Ancient Minister appear as collectable spirits, as does a Subspace Bomb and some of the Army's infantry units (a Primid, a Roturret, Bytans, Mites, and Shadow Bugs). Galleom also reprises his role as a boss in addition to being a spirit.