The provided "roadmap" shows how the engine will be updated, but in no way shows what is expected to be devellopped from a "game" point of view. The way I see it, once the "roadmap" is checked off, then a game can start to be made. What will this game actually consist of? In other words, you have now made a world. What do you plan to do with it?
The game is being done in parallel, once the engine has the features required for a particular gameplay element. For example, with characters and animation and ballistics we can implement the basic shoot-whatevers-moving thing.
Also, the exact gameplay style (or a combination of) will be determined and refined along the way based on the developed game story and feedback from people. Anteworld aiming to be a demo game for OT engine has goals to show the engine's capabilities, so the gameplay style should be able to utilize the large terrain and the ground details, deformable terrain and ability to build stuff dynamically etc.
Will there be hundreds of different types of vegetation customized to the different biomes?
Animals?
Caves?
Clouds/wind/fog/rain/ snow?
Will the world change with the seasons?
Ultimately the biomes will provide multiple different & customized vegetation cover.
Animals - would be nice to have a wide variety, but that requires lots of custom made animations. I think we will start with some birds and will slowly add more. However, since it's not essential for the gameplay and for the demonstration of capabilities, it won't likely reach the richness we'd all like to see anytime soon.
Caves - counting with them, the tech is needed also for tunnels.
Weather - yes.
Seasons - a gradual transition is expected to work in a similar way how transitions between the biomes will work, a parameter driven fractal mixer process that blends between two or more types of terrain material, with accompanying changes in colorization etc.
How many unique players could be in the world at one?
Could this be used to create an ever evolving universe of different planets over the next 10-20 years?
Now this is fairly game & gameplay specific. Needless to say, at the moment we have nowhere near enough resources to make it s massively multiplayer thing in the usual sense. Anteworld will start as "massively singleplayer": people able to conquer a part of the world where they will start building and playing against AI. The changes done to the world will be stored in the cloud, so that other players can see what everybody has done in a shared world, and also to interconnect routes and establish trade later on within the strategic part of the game.
Once we get more resources, this will be further extended to get an interactive multiplayer modes in.
Will there also be damage model for vehicles / planes and so on? 
Ultimately - yes, it's needed for many kinds of simulators that we are going to support. We'll see about the degree to which we'll be going, certainly starting with a simpler damage model initially.
When you mention importing data, including from OSM, does it include building, road, airport, etc. data from OSM? (:
Everything that is suitable for import. Stuff like man made fields/pastures, roads, lakes and rivers. Once the importer API is ready, we are going to test an external sw that reads building data and attempts to reconstruct the buildings from OSM.
However, the consistency and quality of OSM data and metadata is a big question.
