Fukuro and Eddie Owul, a pair of siblings, travel through space to deliver intergalactic home-cooked dishes in spirit of their late mother, whose wish was to spread delicious food across the cosmos.
One fateful day, their spaceship crashes onto an unfamiliar planet called Calpucca. This planet is having a cooking tournament, called the Gourmeet competition, where aliens come to share their dishes to be judged. The winner is granted one wish, and the siblings, knowing this is their chance to wish for their ship to be fixed, enter the tournament.
The duo befriends numerous aliens and residents of Calpucca along the way, some of whom hold mysterious pasts of their own. Calpucca itself holds many secrets, having once been at war with aliens from another planet that they call "starlings".
In the spirit of Segawa's previous, much darker games, the surreal, creepy side content is plentiful, however, it is infinitely more cheerful than its predecessor.
Walking on a Star Unknown contains examples of:
- And Now for Someone Completely Different: A totem can be interacted with to switch between Fukuro or Eddie. Fukuro can understand what sprites are saying, while Eddie can lift objects and doubles the amount of money you gain while walking. Some of the dialogue also changes depending on who is leading.
- Big Eater: Almost everyone in the game, but the most notable ones are Star Goddess (Phrodite) and Eddie.
- Bookends: The game begins with the siblings arriving at planet Calpucca. If they win the contest, the game will end with them leaving the planet.
- The Cameo: Depending on which fishing rod you use on day 2, the "collaborative shelf" in Opti-Mart will have either Farethere City or End Roll merch.
- Contrived Coincidence: Fukuro and Eddie's spaceship crashes on the first day of Gourmeet. And it also happens to land on an empty field in the forest. Should it have landed on the town, there wouldn't be a festival...
- Conveniently an Orphan: The Owul siblings, Corme, and the Hamelin siblings. Averted with Ophelia's, who never shows up in-game but lives in a secluded residence that only Mayflaus can access.
- Crapsaccharine World: Calpucca is a peaceful planet with great cuisine, a kind goddess, and a wise child as its king. But it's still a planet that was once at war with another planet, and some artifacts and buildings from that war still exist. Not to mention the spirits of soldiers that linger in the Yunerium Highway that give aliens a weird vibe or headache every time they cross it.
- Female Angel, Male Demon: Phrodite wears a Holy Halo on her head that makes her look like an angel. Desmond has horns that make him look like a demon, but both of them are gods.
- Lighter and Softer: Compared to any of Segawa's previous games, this game holds a much brighter atmosphere and lighter tone, although it still has its moments.
- Multiple Endings: There are three types of endings: the normal end, the good end, and the [character] end. The [character] end has 12 variations, making it a total of 14 endings.
- Physical God: Phrodite and Desmond. Downplayed with Yurika, who is described to be something close to a god.
- To Serve Man: In the meat shop, there are aliens called "Huemins" who are awaiting slaughter, contained in large dim cages. Approach them, and they will beg and plead for mercy - or hang their heads, awaiting fate. These are heavily implied to be based on real Humans, like you, from Earth. In addition, their meat and guts can be bought and used in dishes.
- Surprise Creepy: There are a few moments to remind the player that they're still playing a Segawa game.
- A notable example is the Yunerium Highway, an area accessed by reading the back of a specific sign. The music is much darker, there are bloodied and mangled soldier ghosts wandering around, and a few jumpscare-esque moments. Don't drink the soup.
- The Stinger: After finishing a character's ending (by maxing their friendship level and giving them the golden medal), a stinger will show Fukuro and Eddie greeting them on Calpucca once again. Except Yurika, who actually goes with them to space.
- War Is Hell: Centuries ago, there was a war between Calpucca and Megalopolis that left devastating damage. The spirits of the soldiers are filled with hatred for starlings, leading to a hatred of any alien, starling or not.
- Worthy Opponent: Desmond acknowledges the Owul siblings as this, wondering if things would have changed if he had met them sooner.