It must have been well over a year ago when the idea of a greener city expansion was thrown out for the first time. I remember briefly checking out some possible assets back then and although I had to turn my attention pretty quickly towards other stuff, I really liked the idea of green cities and what we could do with it art wise.Plenty of rooftop gardens for your green thumb citizensWhen it was time to actually start working on the expansion, it was pretty clear from the start that the amount of new assets would be huge. Adding a whole new style for only residential zoning would mean around 90 new buildings even without variations and we of course needed commercial and office specializations too. On top of that Paradox and our dev team agreed that the player should be able to go all-green with the city which meant that we would also need lots of new service buildings for the expansion. With new props and trees, electric vehicles, few parks & plazas and six new unique buildings plus monument added to the asset list, it was pretty clear that our art-team of seven would have a really busy few months ahead of us.New assets as far as the eye can seeThe amount of assets meant that some of those had to be outsourced. Decision was made that Anatoliy and his team of talented artists at our trusted partner Ulysses-Graphics would do the residential buildings and our own artists would take care of all the rest. We’ve been working with Ulysses many times before, but this time everything was little bit different, because we were after a very specific look and feel. Communicating all these “rules” between our artists and Ulysses was a challenge and required that we have crystal clear idea of what we are doing.Get your dose of healthy weedsArchitecture in Cities Skylines has always been a mix of different styles from around the world, but in Green Cities we needed to be a lot stricter. We needed something that is clearly different from everything we’ve earlier created, but similar with each other so you would instantly recognise new specialization no matter if you are looking individual buildings up-close or the whole district from afar.Green people should be pretty easy to spotWhen you are googling the pictures of eco/self-sufficient buildings, there are few things that you notice almost straight away.Their design is often very plain and modern. Lot of the smaller houses look like fancy boxes and when the bigger ones start to have larger slanted roofs, they still look very efficient and minimalistic. You could even say that in many cases the buildings have kind of nordic design feeling in them. To separate self-sufficient buildings from the earlier buildings in the game, we wanted their design to be more angular and cleaner, but still without being too futuristic. There’s lots of straight lines and you can kind of see the economical and ecological approach in everything.Wood seems to play almost always some kind of role in the design of Eco buildings. In small detached houses and even in some of the smaller apartment buildings, wood is often the one main material. Even in tall high-rises that are mainly made out of concrete, there are usually some kind of wood panelling used to soften the look.New flower trees are the rare colour spots of self-sufficient residential districtsIt is very fitting that buildings that are designed to be good for the environment, have very natural color palette. Largest surfaces are occupied by different shades of wood, white or light grey concrete and natural green from plants and rooftop gardens. It’s safe to say that there’s nothing really adventurous when it comes to color, but to be honest, I really like it that way and along the overall shape of the buildings, it was something that really helped us to separate self-sufficient houses from the regular ones.There’s also those little visual flavours that come from the environment friendly technology. There’s air-source heat pumps, ventilation and watering pipes and solar panel roof tiles that play small but very important role on how the building is functioning and thus how the building looks. For me it has always been very important to take into consideration what the building needs to actually work. It makes it so much easier to come up with small details and those small details are the ones that makes the building interesting to look at.Green technology is icing on top of the building cakeOh, and then there’s terraces. Lot’s of those. Being in touch with the nature seems to mean that people are expanding their livingrooms outside. And I truly root for terraces. After all, I just built one next to our house during summer vacation.Residential buildings were the ones most influenced by these guidelines, but we didn’t want to forget all those visual clues when we started to build commercial and office zones. There’s lots of elements that you can see repeating throughout all the zones and while the it-cluster offices are really different from Eco residential and commercial buildings, there’s still rooftop gardens here and there for game devs to relax on after the launch of their new dlc.IT-Cluster never sleepsIt was really interesting task to create the style for zonable buildings and I’m relatively happy how everything looks, but the most interesting part of this expansion for me was to find out what kind of new technology there is in development to create clean energy for the future needs. And which one of these new ways would make nice looking buildings.In Green Cities there will be three new ways to create electricity and they all are based on real life examples that might or might not be solutions for the future energy needs.Solar updraft tower is based on the fact that hot air tries to rise above the cold air. To put it simple, there’s large greenhouse-like surface surrounding the huge chimney and when the air under the surface is heated by sunlight, it will naturally try to get up thus creating constant updraft through the tower which is the only escape route. This updraft then rotates the turbines on the root of or inside the chimney creating electricity.Game version of solar updraft tower might be small, but it’s very pretty and powerfulIn Cities Skylines we had only one major issue with this building and that might be the very reason why there’s not more of these in real-life. The diameter of the greenhouse - structure can be 8 kilometers and there are plans in place where the height of the tower is over 700 meters. It’s probably needless to say, that we had to scale down our versions a lot, but it was something that was just too cool to be left out.Second new clean energy source in Green Cities is called Ocean Thermal Energy Conversion Plant. In real-life these plants produce electricity by using the temperature difference of ocean waters, but in Cities Skylines it’s luckily much simpler. You just have to place them on your shoreline and connect them to your power grid.Differences in water temperatures harnessed to produce electricitySub-building part of the OTECP was the first one that used our new floating building shader and it will be nice to see what modders can do with it.Geothermal heat is something people have been using since Paleolithic times and what Cities Skylines players have been using since the Snowfall DLC. Before Green Cities player has been able to use geothermal energy for heating but with this expansion, you can now go one step further and use it to provide power to your city. It’s probably the most common one of the three new energy solutions and not that futuristic, but still pretty nice way to get your city up and running.Geothermal power plant looks steaming hotThere’s lots of new stuff in Green Cities and I really hope you find them very useful when you finally get your hands on the expansion. All in all, with it’s 350+ assets Green Cities was huge effort from the team and I would like to thank everybody who worked on the expansion for making it possible! I hope you guys like Green Cities as much as I do. We at Colossal are keen to see what kind of environment friendly cities you are going to create.My kind of green cityCheers,Janne, Lead-game artist at Colossal Order