I was amazed by how much The Subspace Emissary resembles the Kirby games. The painted backgrounds, frequent puzzles, and doors that teleport you to areas with special items are all very reminiscent to Kirby's magical world. The Subspace Emissary has a world map not unlike those of the Kirby games. It also shares the Kirby games' free-range feel; though its levels are side-scrolling, they vast and spacious, and you can go just about anywhere in them. The enemies scattered throughout the levels behave like Kirby villains; most of them are weak in and of themselves, but each one has a specialty and, like Kirby villains, they are strategically placed to complement each others' strengths and to collectively function as formidable obstacles.
The Boss fights had "Kirby" written all over them, except in that the bosses didn't spew out items for you to spit back at them. As in other Kirby games, you have to fight all of the bosses all over again in succession before you can take on the final boss. The Boss Mode that you unlock by beating The Subspace Emissary is exactly the same format as the boss modes of other Kirby games, even down to the teleportation room stocked with recovery items.
The Subspace Emissary takes all of the best aspects of the Kirby games, amplifies them, and mixes them into what I believe to be the single best and most creative fighting game adventure mode in history. It's as if Hal Laboratory's legacy of Kirby games has all been practice for this one epic work of art. I'm SO glad it was Hal and not some other company that made Smash Brothers Brawl!