Portals are twice as efficient. "A strange slab of peanut brittle, holding an ancient cookie recipe. Neat!"
Insane oatling workers
Own 5 portals
Portals are twice as efficient. "ARISE, MY MINIONS!"
Own 25 portals
Portals are twice as efficient. "So I just sign up and get more cookies? Sure, whatever!"
Own 50 portals
Portals are twice as efficient. "We can change if we want to. We can leave our brains behind."
Own 100 portals
Portals are twice as efficient. "This refers to the practice of merging higher dimensional universes, or "branes", with our own, in order to facilitate transit (and harvesting of precious cookie dough)."
Own 150 portals
Portals are twice as efficient. "It's almost like, say, an elder god could fit through this thing now. Hypothetically."
End of times back-up plan
Own 200 portals
Portals are twice as efficient. "Just in case, alright?"
Own 250 portals
Portals are twice as efficient. "A popular verse goes like so : "jau'hn madden jau'hn madden aeiouaeiouaeiou brbrbrbrbrbrbr""
The real world
Own 300 portals
Portals are twice as efficient. "It turns out that our universe is actually the twisted dimension of another, saner plane of reality. Time to hop on over there and loot the place!""
Dimensional garbage gulper
Own 350 portals
Portals are twice as efficient. "So we've been looking for a place to dispose of all the refuse that's been accumulating since we started baking - burnt cookies, failed experiments, unruly workers - and well, we figured rather than sell it to poor countries like we've been doing, we could just dump it in some alternate trash dimension where it's not gonna bother anybody! Probably!"
Own 400 portals
Portals are twice as efficient. "We've found out that if we bake the portals into the cookies themselves, we can transport people's taste buds straight into the taste dimension! Good thing your army of lawyers got rid of the FDA a while ago!"
Two images from the Classic version, left: icon shown in the store, right: appearance in the middle field
The portal is the third most expensive unit in the game. It will give you 6,666 cookies every 5 seconds, therefore increasing the production rate by 1,332 cookies/second. It produces cookies 66.66 times faster than a Shipment.
Buying your first Portal will increase Grandma output by +5 cookies per 5 seconds. It will also cause C'thulhu-like creatures to replace some grandmas.
Because of the high base costs, the Portal isn't effective until many alchemy labs are purchased, and their price multiplied by 27 goes above 1 billion.
The achievement "With strange eons" could be a reference to H. P. Lovecraft's fictional book, within the canon of the C'thulhu Mythos, the Necronomicon. In the Necronomicon, the line "That is not dead which can eternal lie. And with strange eons even death may die." is said to be included.
With the Elder Pact upgrade, each Grandma gets +0.05 base CpS for every Portal. Because of this, the Portal used to be the only building in the game that can directly affect the cookie output of other buildings which aren't the Cursors.
As of V2.0, the upgrade type synergy exists, which makes two building types affect each other's cookie output directly.
The Portal used to only give 3,000 cookies every 5 seconds, but after Orteil heard people complain that it was underpowered, he raised it to 6,666.
The icon for the portal may be a reference to the Oblivion Gates from The Elder Scrolls 4: Oblivion. This seems very likely since the gates were known for being alright to start with but quickly bogged down by endless repetition.
Additionally, the "Deity-sized portals" upgrade may be a reference to Mehrunes Dagon from the same game, as he came through the Oblivion Gate and was shown to be the same size as Akatosh, the Dragon God.
The name and description for the "Sanity dance" upgrade are references to the song "Safety Dance" by the band Men Without Hats, which includes the lyric "We can dance if we want to. We can leave your friends behind."
The achievement for getting 1 Portal, "A whole new world," is a reference to the song "A Whole New World" from Disney's Aladdin
The achievement for getting 50 Portals, "Now you're thinking", is a reference to the games Portal and Portal 2, as one of the series' taglines is "Now you're thinking with portals!"
The achievement for getting 200 Portals, "Realm of the Mad God", is a reference to the MMORPG Realm of the Mad God. It could also be a reference to The Elder Scrolls 4: Oblivion, as Sheogorath was known as the Mad God, and his realm, the Shivering Isles was also referred to as the Realm of the Mad God.
The achievement for getting 350 Portals, "He Comes", along with its mangled text, is a reference to the Lovecraft-inspired Zalgo meme.
The name and description of "Maddening Chants" upgrade "A popular verse goes like so: 'jau'hn madden jau'hn madden aeiouaeiouaeiou brbrbrbrbrbrbr'" are references to game Moonbase Alpha, that features speech synthesizing of player chat and had become small YouTube hit. Some players would flood the chat with said parches in-game, including many others, for comical relief which some others would find frustrating. This could also be a reference to the chant featured in H. P. Lovecraft's 1926 story The Call Of C'thulhu, in which the cultists chant "ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn".