Hello everyone !Included in the free update we are bringing with the upcoming Snowfall DLC, there is a brand new tool being introduced which enables modders/content creators to make even more amazing user-made content for Cities: Skylines.We call that tool theand it allows you to create "Custom Map Themes".As you all well know by now, the game ships with various themes, 5 so far (including the upcoming Winter) and each theme emulates a different "fictional" geographical location.Each element of these themes is created and tweaked to our best to provide a unique city building experience in each environment, this includes visual settings but also collections of buildings, trees and props.With the Theme Editor, we wanted to bring the ability to expand on these base themes so you could create more unique and personal visual variations.You can pick any of our base theme and override most of their properties to make them your own.The Theme Editor, however, does not allow customization of Asset collections as we have previously introduced the District Styles for that purpose, but is focused primarily on the visuals and mood of a map.Without further ado, let's dig into what more precisely you will be able to fiddle with.You can access the Theme Editor in the Tools sub-menu, where the Map and Asset Editor currently hang out.You will first need to select the built-in base theme you wish to start from, this is an essential choice as it is not officially possible to change the base theme afterwards. So for example it is not possible to change from Winter to Tropical.You can also load an existing map theme you acquired from the Steam Workshop or already started working on.Once in the editor, you will notice a familiar interface and a pre-loaded map, which displays most of the features you can tweak. As usual, all the hard work can be done from the properties panels that can be opened from the toolbar at the bottom of the screen.Thepanel allows you to override the terrain diffuse and normal map textures as well as their tiling settings. You can also toggle the detail meshes on/off per layer, such as the decorative grass, the fertile land grass and the rocks in cliffs, and control grass color offsets used for various effects in the game, such as pollution...It is good to know that the sand and cliff normal textures are packed into a single texture in the effort to minimize usage of resources, which is the reason why there is only one tiling slider for both cliff and sand normals.The grass color offsets control the color of the grass in various gameplay-related states.For example, let's say the Pollution offset is (0.03, 0.015, 0.040). In a fully polluted area, this amount would be added to the color when rendering the grass, making it slightly more purple (because the values are the biggest for red and blue). For less polluted areas, the amount is interpolated between (0, 0, 0) and the values given.Thepanel enables control over the water textures and colors.For the water foam texture, some experimentation may be required, the red channel roughly corresponds to the opacity of the foam, while the green channel is mostly used for rendering polluted water.Thepanel is focused on the sky properties. From the sky tint to the dramatic effect of sun rising/settings using Rayleigh and Mie scattering values, moon and sun sizes and so forth...The free camera tool in the lower right corner of the screen may be useful to get a good angle to look at the sky when experimenting with the values in this panel.Thepanel is focused on roads and buildings default textures.The upward road diffuse texture is the main pavement texture defining the look of the roads. It will be combined with the textures of the road assets themselves, which provide things like lane markings and details. The downward road diffuse is for similar purposes but for downward-pointing surfaces such as the undersides of bridges.Building base textures are used for the bases of buildings that are visible on uneven ground. Floor diffuse can be seen through the windows of buildings. Light color palette is used for the night lighting colors for the building windows.Thepanel allows to define temperature ranges for a map theme and the probabilities of weather effect during gameplay.Unfortunately, not all of the effects (grass color offsets and building/road textures mainly) can be currently previewed in the editor, so they will require some experimentation.All textures referred to as normal map are industry standard normal maps such as:While there are no strong restrictions on the texture formats and sizes being used, rgb or rgba images of power of two size (512x512, 1024x1024...) are recommended as we will try to convert and resize other formats and sizes at import time which may produce suboptimal results.After assigning a new texture, the UI for that texture will be temporary disabled as we crunch the texture to the internal format required. During that process, the text "Compressing texture..." will be displayed in next to the menu button in the top right of the screen.Once you are happy with a theme, the saving/sharing process works just as in the other tools. When a theme is ready to be published, check the publish box in the Save panel to make it available when starting a new map.Do keep in mind local assets and workshop assets are considered unique, so the suggested workflow is to share a theme on the workshop before creating a map with it. Then when the map is shared, the custom map theme can be set as a required item for the map in the Steam Workshop.Of course the map theme can also be overridden for existing maps or save games using the new drop-down in the New game, Load game, and Load map panels, which lists all the available overrides based on the base theme your map or save game is currently using.In the future, we plan on adding the ability to load any maps or save games using the currently loaded theme as a preview map for the purpose of better fine tuning and to preview some of the properties that currently cannot be previewed in the Theme Editor, such as the building base texture, pollution related settings and so forth.We also plan on adding support for more values, such as the ability to customize the detail meshes for grass/rocks and gain more control over the fog and weather effects.Finally we will also improve the way to pick a theme override when creating a new game or loading an existing one.That's about it, I hope you will enjoy this editor as much as we do and we can't wait to see what ideas you are going to come up with!Cheers-damsku