Shout Out / Cities: Skylines

• One to Doom 3 when a Chirp is made which states the UAC is planning a mission to Mars.
• Similarly, a possible Chirper hashtag is "#iamthelaw"
• Yet another Chirp remarks on how wonderful hypnotoads are as pets.
• Another is made to Paradox Interactive and their forums with a building called the Paradox Plaza, featuring the Paradox logo on it, describing it as a meeting place of game developers and game enthusiasts.
• One potential chirp◊ refers to a Black Mesa incident.
• One is made to Stargate when it says that an archeologist has put forward the idea that the pyramids are landing pads for alien spaceships.
• One chirp is about someone praising the cleaning robots made by.. OCP.
• And yet another chirp refers to neural transplants offered by DataDyne.
• One of the generic commercial buildings has a logo that reads Fault-Tec. Also, one of the chirps references the GECK.
• A light industrial building tailored for agriculture is named Ami's Baking Company.
• An office building is named AT-AT Mobile, parodying both Star Wars and the AT&T network company.
• Being what this game is a successor to, one of the Chirper handles is William Wright.
• Possibly unintentional, but Chirper is also the name of the Twitter clone in the Neptunia series.
• A low-density commercial building is named M&H Clothing, which is essentially the real-life Swedish fashion company H&M spelled backwards.
• The building unlock for having a 4% tax rate for several weeks is a subtle nod to SimCity 2000, where dropping the tax rate of a starting city to 4% was considered optimal.
• Another office building can be randomly named Prudence Insurances, after the real-life Prudential Financial insurance corporation from Newark, New Jersey.
• One of the eco-commercial buildings in Green Cities is named Edison Shop. This building sells electric cars and is a nod to actually four real-life entities: the Tesla Motors electric vehicle company (the building's logo in-game even stylizes itself after the real-life Tesla Motors logo), the Southern California Edison energy company, Edison International (of whom the firm owns the aforementioned Southern California Edison company), and Thomas Edison (who is best known as the inventor of the light bulb).
• There's one to Dead Like Me. One of the companies that pops up in offices is "Happy Face Travel Agency", a play on the temp agency that George works for. (Happy Time Temp Agency.)
• Two commercial buildings pay homage to both Denny's and IHOP by mimicking their style and are called Penny's and Pancakes International respectively.
• One of the chirps mentions "odd mutations found in some people."
• One of the default city names is Westwood.
• There is a chance you might get a chirp from Piper Chapman.
• One of the "Personal Electric Vehicles" in the Green Cities DLC is based off of the P45.
• The Official Park's description references the infamous Doge meme ("Much official, very park").
• One of the chirps that can appear after placing a park says "#parksandrec"