Option Trees for Roads, Zones, and Objects

In today's addition to the Drawing Board series (which incidentally, I decided to stop numbering; I have a ton of ideas for these articles, and I think it will get a bit unwieldy to be writing "Drawing Board XXXVII" before every title) I want to look in more detail at a feature which I touched on briefly back in my article about accessibility: a system for creating and editing presets for roads. But rather than just being limited to roads, I think this same system can also be applied to other network types, and even to zones, parks, and any other kind of object in the game. I call this system "option trees", as it mainly consists of a nested series of options (either number values, on/off toggles, or selectable line items.) As I mentioned in the Accessibility article, there is nothing particularly revolutionary about option trees, but they have the potential to add depth and power to the UI while retaining a high ease of use. But before I get started, the Disclaimer:

IMPORTANT DISCLAIMER

This series of posts are not to be read as "official" ideas for the Metropolis Project, they are simply my personal thoughts about what some cool game features might be.  The final feature set for the game will be decided by the community and the development team contracted to build the game, and may not include any of these things. More details about the purpose of the Drawing Board articles can be found here.

To begin, here's a brief reminder of what an option tree is (taking roads as an example.) Selecting a road tool would open a dialog somewhere on the screen, showing options for that particular road: width, number of lanes, surface material, elevation, sidewalk width, lighting, etc. I call it an option "tree" because it would present these options hierarchically. For example, a user could toggle an option for streetlights; if left unchecked, this would show no further information, but if selected it would reveal a further set of options for different types of streetlight. Those types, in turn could have different settings like height, color, etc. By nesting options this way, it's possible to add as much granularity to the appearance and function of the road as desired.

Player-created presets could be added to the menu along with standard options.

If this sounds fairly complicated, or likely to appeal only to the most detail-oriented of players, well, it is. That's why, to keep it manageable for the average player, it must be combined with two other features: a user-editable system of presets, and a clear and intuitive UI. Presets would simply be a selection of commonly-used options, roughly corresponding to the Sim City 4 paradigm (street, road, avenue, highway, etc.) These would be presented in the UI as the default road options; a user could select and use one of them without ever seeing the option tree.

By digging deeper into the presets system though, players would have a range of powerful options. First, all the default presets would be editable; If a player simply wanted to change the color of the line markings on the default road, they could easily do so by opening the option tree for the "road" preset and changing the appropriate setting. But beyond this, players should be able to create and save their own presets: next to the default road options would be a "custom" road tool, which would not only allow the player to build a road type from scratch by going through the options tree, but to name that road type, save it for future use, and add it to the default road menu alongside the other presets.

To make presets even more flexible, the presets could follow a global hierarchy within the game itself. That is, a set of global tool presets for any new game you start could exist, and be editable, outside of the actual game, whether in the menu options or in a completely separate configuration utility. Changes to those presets in-game could either be saved to the global settting, or as a local setting for that particular game. Newly created custom types would work the same way: you could save them for use only in that particular city or game, or globally for reuse in other scenarios.

An example of how an option tree for a custom road type might look.

One last feature about option trees is that they should (at least for some options) be editable post facto. In other words, it should be possible to change some properties of a road after laying it down. This would prevent the crude and unrealistic paradigm that exists in many city sims now, where "upgrading" a road means bulldozing the entire thing and building a new one; If a player wanted to, for example, add streetlights, they should be able to open the option tree for a selection of roads and toggle the "streetlights" option (at some cost, of course!)

Some of the potential options might be:

• Width: Either total width, or per lane.
• Number of lanes: With a function to specify how many for each direction.
• Surface: Dirt, gravel, or different types of pavement.
• Elevation: A sub-tree of options for height, structure type, etc. would become available if the road was elevated.
• Drainage: Adding ditches or storm drains would cost more (or make the road more unsafe, perhaps, in the case of ditches) but raise throughput for cities with high rainfall.
• Streetlights: Various designs with varying luminosity would cost more but add to the safety rating.
• Sidewalks: Would be more expensive and take up more space, but would encourage pedestrian traffic and add to safety.
• Bike Lanes: A similar tradeoff to sidewalks, but with the effect of encouraging bike traffic.
• On-street parking: Would increase congestion but bring in revenue from permits, meters, and tickets.
• Benches: Increase aesthetic rating and encourage foot traffic.
• Intersections: Intersections would have their own substantial sub-tree, with options for stoplights, crosswalks, turn lanes, etc. editable on a global or individual basis.

While I've been mainly talking about roads thus far, almost any game object could use exactly the same system to define presets and allow for granular control: Railroads could be set for certain types of train (passenger, freight, light rail); Bridges could be selected by structure, material, number of lanes, allowed traffic, and toll/free; Parks could be set for tree density, footpath coverage, and facilities. Even the base zoning tool could follow the same paradigm: a zone could be set to a base type like residential or commercial (or more than one, to allow mixed-use) and within those categories have a wide range of options like allowed building height, resident density, etc.

A system like this would need to find a balance between a healthy number of base types and a reasonably lean option tree (For example, by adding an option for "allowed vehicle types" to the road option tree, you could combine bike paths and foot paths into the same base type as roads and highways; but you risk an overwhelmingly large option tree for that one type.) Not only would a system like this give the developers a solid framework for adding a large number of features, modders would have an easy way to improve and expand on the default menu choices. All in all, I think that this would add enormous power and flexibility to the game interface.