Procedural Generation, Done Right.
Alien Sun is what an exploration-focused space sim should be -- one where the true goal is to see everything you can of the alien worlds around you. Yes, there will (eventually) be combat, trading, and mining, but not in such a way as to get in the way of that core of the game. Your true goal will simply be to see something new and imagine someplace far, far away. Everything here is grounded in reality -- distances and scales are approximately accurate, shading is derived from physical formulae where possible, and names are definitely plausible, but the gaps are filled with possibility and intrigue.
Yes, it's nowhere near complete, but the basic idea is down, the core engine is done, and development is indeed proceeding.
[W, A, S, D] ---- Movement
[Mouse, Q, E] ---- Turning
[R] ---- Free / Lock Mouse
[Left Click] ---- Select / Deselect Object
[G] ---- Go To Selected Object
[ESCAPE] ---- Exit To Desktop
[F1] ---- Show / Hide UI
[F11] ---- Enter / Exit Fullscreen
A relatively modern dedicated graphics card and fairly recent CPU is required to run this, with OpenGL 3.3+ and Java 7+ required: That's the price you have to pay to display, you know, a whole richly-detailed interactive 3D universe.