The idea was to make a kind of earth re-colonization game, where players start to build on our home planet again, after being forced to withdraw from it a long time ago (for whatever reason) to space or underground, taking documentation and conserving some existing machines & vehicles so that they can kick-start the civilization again when it will be possible.
Upon reentry the effects of previous human civilization are long since eradicated, with nature reclaiming the cities and almost everything else man created. Players will start with modern tools and vehicles preserved from our contemporary or a slightly more advanced age.
Note that this background is specifically tailored to satisfy certain limitations we as a small independent developers have got - the game shouldn't be too demanding on our sparse resources (like modeling), while at the same time it should demo the whole planet and procedural capabilities of the engine. So we would provide only the procedural content - showing the planet as if from 10,000 years before now (or say 500-1000 years into future without man) - while the players themselves would provide the content to liven up the world.
The game should include two main modes at the beginning:
Online here means that the game world state would be stored in a cloud system such as Google App Engine, and people will be able to see the creations of others around the world, trade with each other, actually seeing the transports as they go. That means that AI or scheduled traffic will be visible, but not so the direct actions of other players - or at least not until there are special servers capable of handling the real time traffic. There's one possibility that can do without such servers that could be applicable in this scenario - player's own computer (or a player's dedicated machine) may be used as a server for limited number of "visitors", handling the assigned area or event. For example, such an outside server could be used to control vehicle racing events organized by players. But any of this will not be essential for the game mechanism itself.
This design will allow for massively online world without having to care for server side infrastructure. Costs of online access and cloud computing should be included in the price for some initial period, but later it will have to be covered (for online access mode).
It will be basically a slowly running (as opposed to the usual clickfests in traditional RTS games) transportation and world-building game where one can design his city and lands, but also to directly control the vehicles to transport resources and goods, or to explore and prospect the land for resources to be mined, to build road and rail networks, interconnecting with others and building the economy if he wishes so.
As the development advances there might be even further dimensions to it, like a political system and wargaming, though that would require separate game modes so that it doesn't mix up with the peaceful part.
Apart from building and transportation and economy there will be also a first-person style game play, with tasks and quests like cleaning up the area or recovering artifacts from city ruins. The conditions and danger will change during the periods of day, during night or fog ...
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Initial alpha version will focus around the exploration, driving and flying a limited number of vehicles. These should cover major vehicle types, with more vehicles coming later also perhaps from the community.
Online account will come with the possibility to own certain amount of land that can be used to build on solely by the owner. The exact mechanisms how this all could work have yet to be determined.
Mods should be normally possible and encouraged in the sandbox mode, but even for the online mode the mods that fulfill the requirements and get accepted may be included into game. For example, by default there could be one type of truck used for transportation that will be available normally, with different bodies (dry-bulk containers, tanker bodies, stake bodies and box bodies - taken from Transport Giant). Custom truck models may become available as someone makes them, and the additional motivation may be in slightly better parameters than the default ones.
Other types of mods might be possible too, although for the online game play it must be considered carefully.
We would like to try the indie development model (known for example from Minecraft), when the game is released early in alpha stage for a reduced price so that enthusiastic gamers can support and even direct the development, getting all further updates and the final release for free.
When the in-game tools become more evolved, we plan to support multiple realms where users can create and live. Not all users may want to share and build the same world with heterogeneous others. Realms would allow community managed worlds, with community managed access rights ultimately with custom game play rules (or supporting entirely different games or simulators in the end).
This can be also used by game developers to create custom realms as parallel worlds where they will be able to create their own game scenarios. That includes their own models, scripts or game code modules. The worlds could be persisted locally for lone developers, or in a cloud storage for distributed teams.