Space is Fun
You will have a fair amount of flexibility in the game that you create.
The main thing you will be graded on is whether its fun to play - is it entertaining, is it easy to use, does it look cool, does it move smoothly, etc. And of course it cant crash. I will create a small panel of judges who will rate the entertainment value of the games.
You will need to move from star system to star system. You could either have each 'level' take place in a different system, or have the player move between systems as the game progresses
The game can be serious or humorous.
You can go around blowing things up and killing people and doing other politically incorrect things, or you can go around saving endangered space-creatures from the evil capitalistic expansionist humans and be politically correct. Whatever.
For example:
You could do a version of space war (or asteroids if you would prefer to blow up rocks rather than aliens) within a given solar system where the (enhanced) gravity of the sun and moving planets make a more dynamic space to play. Every time you win you move onto another solar system.
You can fly around the solar system in first person view blowing things up (aliens, rocks, tele-tubbies, etc) and docking at bases and collecting fuel supplies and rescuing people in orbits around the various planets.
You could come up with some variant of pool / snooker that uses planets.
You can import models into your game, but you need to clearly identify where you got the models from.
Adding audio can make things more entertaining.
The user can move almost instantaneously from one star system to another. Within a single star system the user should move at some appropriate (though probably physically impossible) speed based on what you saw with the 'ping' in project one. You may also want to slow the user down when they get near a planet.
Or you could do a completely realistic game where nothing moves faster than light, and objects move at some small fraction of the speed of light, where time begins to dilate as you get closer to light speed, and the further you look out the further into the past you look - just be sure to allow the user to speed up time for all the 'boring' parts.