After releasing 2 full expansions every year since the launch of Cities: Skylines, expansions seemed to dry up after 2020. Sunset Harbor released in March of 2020, and there hasn't been any full expansion since then. I'm not sure if this is the result of Colossal Order shutting down its studio temporarily during the COVID-19 pandemic, or if they have just been busy working on a sequel. I had assumed that Cities: Skylines was done, and that Sunset Harbor would be the final expansion for the game. But that is not the case, as a new expansion was finally released at the end of January 2022.
The Airports expansion is yet another expansion pack using the area-painting mechanic that was introduced in the Parklife expansion in 2018, then re-used in Industries and Campus in the subsequent years. As such, I don't know that I really have much to say about Airports. A lot of the same compliments and criticisms that were already applied to Parklife, Industries, and Campus also apply here.
Campus, ironically, did not teach Colossal Order any lessons
The modular nature of the airport buildings, taxi paths, and runways provides quite a bit of customization. There are 3 styles of airports: a retro-style, a modern style, and an "ultra-modern" style. They are functionally the same, so don't fill different roles the way that different parks, industries, or university types did in their respective expansions. The airports are massive and expensive, but they can be shaped to fit into irregular spaces in or around your city. Unfortunately, there's not nearly as much expressiveness as what we were offered by Parklife.
Airports come in different styles, and are customizable (parking lots and garage are mod assets).
Of course, Airports suffers from the same problems that have plagued the previous expansions that used the leveled-areas concept.
A lot of the modular components are simply decorative and have no function other than to increase the area's abstract "attractiveness". In the case of airports, these include the various hangars, parked planes, and so forth. Even the air traffic control tower is a purely decorative object, rather than being necessary for the airport to work!
I've also never liked how the park areas (and now the airport areas) level up by increasing the total visitors, and industries level up based on the total goods produced. This is something that is easy to achieve by simply waiting in-game months or years for the number to go up, regardless of the size or quality of the park, industry, or airport. Because of that, it can be easy for an airport to jump out ahead in total visitors, such that the area can be leveled up immediately, and at any time, by simply placing new structures that bring the attractiveness up above the required threshold.
Airports level up based on the total passengers, which can be easily increased by simply waiting.
Instead, I wish these areas would level up based on the weekly visitors (or good produced, for industries), rather than the cumulative total. This is a much better metric of the capacity of a park, industry, or airport. This is one of the things that the Campus expansion did a bit better than the others, since the universities level up based on the current number of students (rather than the cumulative total of all students who have ever attended the university) and the number of research projects. The amount of students is capped by the size of the school, and the research projects are semi-randomly created based on the funding levels and access to research facilities.
Airports aren't like that. Leveling them up feels much simpler and requires less effort and management from the player. Airports also cannot de-level (like universities could) if you fail to maintain its attractiveness, and since total passenger count is something that can never decrease the way that a university's student attendance can decline -- or the way that weekly passenger count could potentially decrease.
And when it does come time to level up your airport, you can't simply extend the runway. You have to tear the whole thing down and build a new one, which will also probably require redoing all the taxi paths as well. Pain in the ass.
Legacy airport ploppables feel completely obsolete.
The legacy airports still exist in the game, and so they feel mostly redundant. They can serve as cheaper alternatives to an airport area, with a smaller physical footprint, but other than that they are pointless to build.
Again, this is an area where the Campus expansion excelled compared to the other similar expansions. The Campus universities are capable of taking in exchange students from outside your city, which could leave your city's actual population under-served with regard to higher education access. As such, the legacy university ploppables have a useful role as sort of "community colleges" that exclusively educate your local population.
Airports does not do anything similar. I cannot find any functional difference between the legacy airport ploppables and the new airport areas that would give any sort of niche usefulness to the legacy buildings. They might as well not even be in the game.
Small city, big airport
The new airport areas are also available surprisingly early in the game. I think it only requires 5,000 population, which is only like the third or fourth milestone. This is a couple milestones earlier than the legacy airports become available. It's also earlier than high-density zoning, oil industry, and universities. And since the advanced airport buildings are locked behind airport levels instead of population milestones, it's entirely possible for tiny cities to have massive international airports.
Small cities can build airports early if they just save up some cash.
The only counter against this is that airports are very expensive, which makes it unlikely that they can be built as soon as they are unlocked. Just getting a terminal and runway down will cost around $200,000. But this can be achieved by simply speeding up the game and waiting for the money to trickle in. It's difficult to do, since cities this small won't have access to waste incinerators or crematoriums, so landfills and cemeteries will fill up, forcing you to buy more, which will sink a lot of your money and take up a lot of space. So you're better off waiting till your city is bigger and wealthier before building an airport anyway.
Honestly, I don't know why Colossal Order didn't just wait to unlock the airport areas until at least the same milestone as the legacy airports. I guess they didn't want people to have to wait too long to use the new stuff?
Planes, trains, and automobiles
As usual, the new expansion also comes with some free updates that every player will receive regardless of whether you buy the expansion. Some of these are pretty valuable updates that will be welcome by anybody still playing Skylines.
Buses, trains, passenger ships, and so on have higher passenger capacities,
reducing the number of vehicles that spawn and cutting down on congestion and log jams.
There are new options for selecting different variations of service and transit vehicles. For transit vehicles, this can be done on a per line basis, and some variants also come with higher passenger capacity, which means fewer vehicles are needed to transport passengers. This can help to reduce the congestion and log jams with trains and busses that happened so frequently previously.
The dev diaries also suggest that other services, such as fire, police, and ambulances can also use different vehicle variants, but there was no option for me to do so in any of my cities' service buildings. Maybe it's because Colossal Order does not provide variant vehicles by default for these services, so the only way to get them is from mods? Mods that I don't have? It would be nice to also have higher-capacity garbage, post, and freight trucks, so that those don't also clog up my roads so much. I guess I'll have to go to the Steam Workshop and look for some.
The need for airports to be on completely level ground has also lead to some refinements to the terraforming system. Terraforming soil can now be bought and sold to allow for more massive terraforming projects in mature, wealthy cities. This does lessen the influence of the underlying terrain on the later development of such cities, which is a bit of a shame. But the high cost of buying soil and the low cost of selling soil makes it prohibitively expensive for small and medium-sized cities, so there's still some balance. Large, wealthy cities, however, can now basically terraform as much as they want.
Terraforming soil can be bought and sold.
But then, of course, there's also all the stuff that Colossal Order didn't but into the expansion. As usual, it's not necessarily fair to criticize the game for what I want it to be, instead of what Colossal Order wanted to make. But in this case, I think it's particularly apt, since the Airports expansion is so skimpy on content.
First of all, there's the thematic stuff that could be included, but isn't. There's no private aircraft hangars or runways. There's no pontoon plane docks, helicopter pads, or other alternative aircraft options of any kind.
There's also only a single unique aviation building. It's a museum. I'm surprised to not see any kind of special airports like maybe an air force base. Maybe it could give the ability for the city to put on air shows with either historic or modern aircraft.
Airports also have a "Rental Car" policy that allows passengers to purchase rental cars for use in the city. But it's just a policy. There's no infrastructure for it -- no rental car lot. This would have been yet another perfect opportunity to introduce parking lots and garages into the game, as well as "Park 'n' Ride" mechanics. Once again, if we want such infrastructure, we have to get it from mods.
And, of course, there's still the long legacy wishlist of items and mechanics that I wish Colossal Order would add to Cities: Skylines, but which are still frustratingly absent. Though, to be fair to the Airports expansion, these complaints aren't really within the scope of the "airport" theme -- or if they are, it's really tangentially.
Airports continues a long trend of Skylines expansions leaving out things I expected to see.
There's still no public beach park areas, which should have been part of Parklife, but wasn't. There's still no way to assign shipping routes for cargo ships or daisy-chain cargo harbors to go into bays or up wide rivers, which should have been part of Mass Transit or Industries or Sunset Harbor, but since it wasn't included in any of those, I'm going to keep complaining about its omission. We're still missing official assets for things like neighborhood athletic parks like soccer fields, baseball diamonds, and so forth. There's still no mechanics for urban decay. And so on, and so on. Hopefully, stuff like this will be in Cities Skylines 2...
Sunset Harbor was a disappointment, but Airports might take the cake as the weakest expansion for Cities: Skylines. At least Sunset Harbor gave us something that we didn't already have, in the form of the fishing industries. Airports doesn't give us anything that we didn't already have. It provides the ability to build commercial airports. That's it.
I hope Colossal Order is working on the good stuff for a sequel.