I've been really thinking about the concept of travel, control, and time. I've been trying to think of "slow control" methods of travel. That is, methods that are more introspective than the standard rapid running & platforming segments.
Things like sailing, orbital transfer, gliders, leaping long distances, swinging, and "quick climbing" (dashing up the side of things) are all good examples of what I'm talking about. These methods of travel rarely challenge your reaction speed or require you to dodge obstacles. Instead, they're about looking ahead and tweaking a bit so that you end up where you want to be in the future.
I wracked my brain trying to think of a method of travel that really seemed interesting and tangible. Something that would involve a few different modes, an organic feel, and that "slow control" method.
And I came up with the Sun Wing.
This takes place in a slightly fantastical future where there's not really any rocket fuel left. Reaching space is only possible via Sun Wing.
The Sun Wing is a very adaptive, technologically advanced not-quite-glider. Near the ground, it operates like a glider.
However, it has several engines in it.
One is the electrical jet turbine. This can't keep the vehicle aloft forever, because it eats through electricity faster than the solar paint can replenish it. It mostly serves to increase speed in the upper atmosphere, helping take you into suborbital arcs. It can be used low and close to the ground, if you like, but it's less effective there.
Another is the afterburner. The vehicle wicks water out of the air and converts it into hydrogen and oxygen. This happens really slow, so the vast majority of this happens on the ground in time acceleration. You can use that and the jet turbine to create a powerful "afterburner" effect, normally used to launch off the surface and into the air. Used effectively, this will last long enough to get you high enough for your jet turbine to take over. Used ineffectively, it's a fun way to give you a little added duration to your flights. It can also be used to help land by firing retrojets just above the ground.
At lower altitudes, you'll use a hydrogen-heavy mix, preserving oxygen for breathing purposes. You can use it in the upper atmosphere or even in deep space, but you'll burn your oxygen very quick.
The third and final engine is the ion drive, which is used for non-atmospheric maneuvering. IE, going from sub-orbital to orbital and back. The ion drive can be as powerful in space as the jet turbine is in the atmosphere, but you aren't going to have the electricity to run it at that level: it's even more energy-hogging than the jet turbine.
These three engines combine to give the player a lot of control over how they get around. They can glide around near the surface, fly in the middle altitudes, or even enter space. In theory, you could even reach the moon on a Sun Wing... except, of course, for the pesky need to breath. Even with scrubbers, the oxygen you take with you is pretty limited. You have to watch your weight, after all.
There is another facet of the Sun Wing: it has a very adaptive surface. The higher in the atmosphere it goes, the wider its wingspan becomes. This keeps your lift pretty constant even as your air pressure decreases. It also radically increases the solar paint's surface area, so you get a whole lot more electricity, making your jet turbine and ion engines feasible to run continuously.
When you leave the atmosphere, your flying rig stops looking like a sleeping bag with arms and inflates into a small but comfortable little tent. You can do this when parked, too, but like the extended wings, you can't really do this in dense atmosphere because it'll tear apart. Anyway, you can go from "rigged for flying" to "in the tent" whenever you like once it's open, and when you're in the tent you can see orbital paths, science experiments, emails from the surface, and so on.
The actual GAME part of this thing involves interacting with people on the surface. There are still plenty of people in this fantastical future, although there are very few compared to the 8 billion we have. More like a million, living relatively easy lives with an incredibly high level of technology. Most of them are interested in trading, or in giving you scientific missions.
There are five categories of task, although they certainly aren't exclusive and you can often do several at once if you figure out how.
Salvage/survey is the most basic mission. Because the population is so low, most of the world is empty of humans. While the maps of these areas are generally accurate in a topological sense, you can often find things that aren't topological. An old computer that still works, a junkyard nobody's raided, a cache of DVDs... some you can actually load into your cargo pocket and fly away with, while others you'll need to tag for pickup by whoever is closest. The advantage of loading it into your cargo pocket is that you can deliver it to wherever you like, while tagging always benefits the person closest to you rather than whoever you like. Either way, you get credit.
Cargo missions are pretty straightforward. Everyone is willing to trade, whether in credits or barter. Sometimes you'll run with whatever cargo you happen to want to, other times you might get a specific cargo with a specific delivery requirement. Because every pound added to the Sun Wing makes it harder to travel, you'll usually carry very low-weight goods such as data chips, computer components, spices, genetic samples, DVDs, and so on. You can carry heavier goods, but to do that you'll generally want to take off from a zeppelin or carrier, which limits where you can start from. Of course, not all places are easy to land in, either...
Data missions are a staple. Because of the heavy debris fields in orbit, there are few satellites. Therefore, you'll often find it useful to stand in as a temporary satellite, relaying transmissions, taking pictures, and so on. You may even be asked to deploy a temporary satellite as cargo. There are a few similar missions that happen in the atmosphere, normally wind-mapping, but this is primarily an orbital/suborbital thing.
Manufacturing missions might be possible when you've upgraded your wing, or launched from a zeppelin. The rig for manufacturing things is sometimes a bit heavy, but the point is that certain things can only be manufactured in orbit, whether because of the zero gravity, the magnetic fields, or the radiation. Manufacturing normally has strict requirements about the conditions - for example "only in the shadow of the planet" or "only when passing over the poles". Because of this, an understanding of basic orbital mechanics and a steady hand on the time accelerator is required or you'll end up corrupting the batch.
Lastly, there's space ops. This generally involves refueling and maintaining the few satellites there are, although you can also salvage from debris fields, perform debris cleanup, and even launch new permanent satellites if your wing has been upgraded to the point where it can carry that kind of payload.
It needs to be stressed that these missions aren't for the sake of doing these missions. Every mission you do, whether it was a request or just something you wanted to do, improves the life of a local. The more resources and connections a local has, the happier and healthier they are, and the more friendly they are to you. Obviously, with a million random people, it's not like every one of them then turns around and gives you an upgraded Sun Wing module, but everyone at least contributes what they can. Whether it's a paint job, a pretty picture, some clothes, or just agreeing to store your stuff for you. And, of course, they help each other out - someone who can't give you anything will still help all their neighbors, which effectively means you went on a bit of mission for them, too.
The world is large, so part of the fun is exploring the surface bit by bit, and finding some places to call "home" with people you like to help and hang out with between missions. Of course, you can use time acceleration to blitz through every landing and spend almost all your player time in the sky, it's up to you.
All combined, the idea is to have a kind of movement that is a lot of fun, transitioning organically between glider, jet, and spacecraft. The somewhat complex array of resources to manage during flight gives you a level of fine control over things like how long you can stay in space, and there's enough skill involved that you can polish your skills for a while.
The setting gives you a bunch of resources in a lot of places - some reliably in a given place, some that need to be stumbled across, and some that are midway between. The steady improvements to yourself and the human inhabitants gives the world some constructive longevity.
There is also a lot of opportunity for multiplayer, whether with NPC Sun Wings or other players. Docking up in space, landing together, trading tech modules, transferring cargo or fuel in midair, creating transmission networks out of spaced-out Sun Wings so that people even further apart can communicate...
In the end, the point is to have a design that can be easily implemented at the most basic level (the mechanics of the glider) and then easily expanded to include the rest of the stuff. Hopefully, that will allow me to release iterative demos, each of which is fun to play in its own right.