|First Level||Laboratory 1|
|Latest Level||All The Way Down Hard|
|Appearances||175 (include Endurance, Flashes)|
Grey Goo is the main character. He can eat anything that is smaller than itself. When Grey Goo eats something, it's supposed that that thing would be killed or destroyed, its colours inherited by the goo himself. For an example, when he eats a green candy, he turns green as the candy gets absorbed into his mass.
- In Tasty Planet his story begins with the scientist that created him. The scientist gives him candy, allowing him to grow large enough to escape and feed on the outside world. He eats microorganisms in the laboratory, then travels outside, onto a picnic table, into an ocean, then in a park, to a city, then launches itself into the sky, then in orbit and finally into the Cosmos.
- In Tasty Planet Back for Seconds his story begins the same, but he first eats the laboratory's small objects, instead of microorganisms. Then he eats the time machine and teleports himself into the Late Cretaceous, then into Ancient Egypt, to Ancient Rome, then in Feudal Japan finally in the Distant Future.
- In Tasty Blue he's absent, but can be spotted on the sign in front of the research facility in the Arctic where Nano-shark is introduced.
- In Tasty Planet Forever his story is rather different this time but similar to how it plays out in Distant Future. It's shown that he was frozen in a block of ice on Mars in the year 2057 and was eventually thawed out into a small water puddle on the floor of a Martian building. This time he starts out smaller than ever where he's the size of a quark, but still resides in a water droplet like in Distant Future. He begins to grow and eat the Martian colony and eventually the universe, and by eating the universe, it's shown that the universe is just a quark itself meaning that Grey Goo can eat forever and ever eating different universes, hence the name of the stage, "Forever Feast".
- In Tasty Planet, when he finished the final level in Laboratory, he travels Outside. He started on the ground, he eats Clumps of Dirt, Big Clumps of Dirt and grow bigger to eat some insects like Aphids, Ladybugs, Flies and more others objects like Bonsai Leaves, Seeds, Pine Needles,Twigs,...
- After a while, he saw the scientists, who are playing dominos on the Picnic Table, and Grey Goo jumped on the table and the scientist are surprised, though they thought he is just a Mouse, then they keep playing dominos and eating. On the table, there are many fruits, and there are Pennies, Dies, Blocks. When lunch time, there are Cheeses on the table, Mice and Rats that came close to the Cheese and eat them, but Grey Goo eats them first and then he eats the Cheese too. Not only Cheese in the lunch time, there is also a Grapefruit, Chocolate Milk... When he grows bigger, the scientists discovered that it is he, they grab and capture it in the tablecloth, then they run with it to the seaside and the Old Scientist throw the tablecloth with he inside it in the Ocean, to make sure he gets eaten by fishes.
- In the ocean, he saw many types of fishes, dolphins sharks, which try to eat fishes smaller than them, and so does he. Then he stoped growing bigger when he was shrunk by the flick of a whale, the whale flick him into the mainland. Then he travels to the Park, where he meets Rats first.
- In the Park, there are many sport objects, Golf Balls, Baseballs... Also there are many of animals like Mice, Rats, Cats, Dogs... Those animals are eaten or chased by bigger animals. Not only animals, there are humans there, Women, Men, Police Officers. When he grows bigger, he travels to the City.
- First objects he is supposed to eat is Stop Signs. In the city, there are many types of Trees, also there are many of people trying to escape, some will try to stop him, like Police Officers, Police Cars, Tanks... When he grows even bigger, he eats Trains, Houses, Buildings and everyhing smaller than him. After that, at the scientists house, the scientists are watching the news channel which is talking about Grey Goo and how he ate half of the City, then he jumps into the Sky.
- In the Sky there are many types of clouds. Also, there are many types of flying objects, like Birds, Kites, Biplanes,... and other bigger objects. In the Sky, there are Fighter Jets, which are trying to stop him from eating everything. When he grows bigger, he travels out of Earth, into the Orbit.
- In the Orbit, he is eating material like Meteroids, Asteroids... Not only that, there are many Astronauts in the Orbit, however in real life there aren't that many people. He is not the only one who is eating smaller objects and grows bigger, there are also Energy Entities. There are also Attack Shuttles whcih are attacking him. Before he travels to the Solar System, he need to eat the Moon first.
- He travels to the Cosmos, in there, he eat the planets in Solar System, then he eats Stars, a Black Hole, Nebulas, Galaxies,... and finally the Fabric of the Universe and Time Itself. When he eats the whole Universe, he explodes and the Universe starts again.
Tasty Planet Back for Seconds
- When he ate the Time Machine in the final level in Laboratory, a green light appears inside him, then he disappears from the Present Day. The Young Scientist asked where he went, then the Old Scientist answered that he traveled back to the era of the dinosaurs, where he first met Aphids.
- In the Late Cretaceous, there were many types of Insects, just like the Insects that are living in the present: Termites, Ants, Larvas, Butterflies,... Also there were many types of plants like Mushrooms, Oak Trees, Maple Trees... and many types of ancient organisms like dinosaurs, turtles... After he fed on dinosaurs and dwarfed them in size, he ate Redwood Trees and Lava, along with larger objects such as Mountains and a Volcano. Upon consuming the volcano, the meteorite that was supposed to kill the dinosaurs appeared and struck Grey Goo, being devoured in the process instead of impacting the Earth's surface. Meanwhile, in the present, dinosaurs suddenly appear outside the Labratory, and the Old Scientist explains that dinosaurs never went extinct because the meteorite never hit the Earth and caused a nuclear winter. Grey Goo suddenly vanishes from the prehistoric era, and the Time Machine transports him to Ancient Egypt as a tiny piece of grey goo.
- He started on a table, where there were many insects like Larvas, Scarabs, Locusts,...; along with many types of human's jewelry and many of other objects. When he grew bigger, he jumped off the table and ate everything smaller than him in the room, including the Egyptian Workers and Soldiers . Then he traveled outside where he ate humans and animals, before the Houses, Sphinx and finally the Pyramids. After the Pyramids were eaten by Grey Goo, there were breaking news in the present day, talking about the missing Giza pyramid. Meanwhile, he is shrunken again and travels to Ancient Rome.
- He started on a table again, only that there were many fruits and fish along with other objects. Much like in Egypt, when he grew bigger, Grey Goo jumped off the table and started eating everything smaller than him. Then he grew even bigger and ate the entire Roman Empire, finally topping off his appetite with the Coliseum. At the scientist's laboratory, the Old Scientist is suddenly wearing a toga, explaining that the citizens of Rome were forced to unite together and rebuild their civilization because of the destruction caused by Grey Goo. Like in the previous chapters, Grey Goo then shrinks and travels to a new time period, in this case the world of Feudal Japan .
- He began on the ground, surrounded by cherry blossom flowers and grains of rice. He ate those objects and grew larger like in the previous chapters, first eating rocks and shurikens but then moving on to ninjas, samurais, and eventually houses and cherry blossom trees. Finally, Grey Goo swallowed Monsterzilla, the only protection for humans from the various monsters that inhabit Earth. Seeing King Kong, Mothra, and other monsters attacking the present-day society, the scientists decide to freeze their brains in jars, so they could be prepared for the next time period when Grey Goo shows up, which was in the Distant Future .
- He came into the Distant Future at a microscopic size, around a bunch of bacteria and other microscopic organisms. The scientists try to kill Grey Goo with nanobots and lasers mounted on rats and ants , but were hopeless. Eventually, he grew large enough to be seen without a microscope, and consumes the brain jars of the scientists who made him in the first place. He then feeds on the advanced society of the future, and escapes into the cosmos with flying saucers as the humanoids' last line of defense against his massive appetite. Still, the humanoids could only sigh as Grey Goo swallows their planet whole, and moves on to feed the Solar System and Milky Way Galaxy. At last, after eating many star clusters, Grey Goo began to eat the fabric of the known Universe, which happened to be on the back of a "Turtle of Time," a turtle stacked on top of an infinitely repeating stack of other Turtles of Time. There was no way for the turtles to defend themselves against him, and he ends up having an endless feast for the rest of time.
His apparance is that of a slimy grey ball with 2 adorable eyes.
In Tasty Planet, his eyes are above his head, and there is more goo radiating out. You can change his eyes and his appearances when you complete the normal mode and the casual mode. There are big eyes, small eyes, cyclops eye, wide eyes, in eyes settings, and rainbow goo in appearances settings. When you choose rainbow goo, your normal Grey Goo turns into a goo that is changing into every color. You can also choose one of the many settings at once. For example, if you choose wide eyes and small eyes, wide small eyes are the result.
In Tasty Planet Back for Seconds his eyes are in front of his head, and there is less goo radiating out, if you played local co-op with friends, the second player has one eye. He can eat other Grey Goo in the following levels: Dinogoo, Googyptian and Gooturistic. In these levels he needs to grow bigger, or else the other goo will eat him before he can eat them. Also if they grow bigger, they move faster, not same as grey goo who is controlled by players.
- "Woopah!" (often misinterpreted as the Greek saying "Opa!")
- "Oaaa" (touch and another goo Poofed)