I think this is a good idea. Always make things better. Hi.
1. Different sizes and kinds of stars
2. Solar systems move faster than the planets going around a star. Stars orbit around a black hole. This would affect how fast a spaceship would travel, but I don't know the physics behind this.
3. The galaxy in Galactic civilizations is a little unrealistic stars are not usually yellow but red. Most planets are in a in a pluto like orbit. There are multiple star systems. These stars usually go around a center that is either nonething or a neutron star.
4. neutron stars or white dwarfs.
5. rogue planets can be terrestrial may be habital. Sub brown dwarfs can have a mini solar system. It is possible for a rogue planet to be moving into a solar system. It is possible for a planet to get ejected from a solar system. There r twice as many rogue planets as there r stars.
6. A star that goes supernova still may retain the outer planets.
7. Asteroid and comet belts go around the solar system. inner r rocks outer r ice. Comets can be dislodged and go around a star or hit a planet. Comets r usually larger than astroids, move faster, and the big ones r more plentiful. In considering at least in our solar system there r a lot more ice than there is rock, and the common size of the ice is a lot larger. Large enough to be more massive, and 2 or 3 times faster. Gas giants and dwarf planets do a lot to block this. All planets have near planet astroids. These r more likely to hit them than the astroid belt. The size of the debris depends on the age of the solar system. In a young solar system the orbits of the planets r unstable and 2 planets may share the same orbit. U can have up to 100 planets in a young solar system. Lets not forget the proto plametary disk that makes a solar system. Lets not forget the oort cloud that is made up of objects of ice, rocks, proto planets, or ex moons. Gas giants and ice giants r the planets from the solar system that creates this unstable orbit. A gas giant can be as close as 100 kilometers from the sun. For gaming purposes the astroid belt would only contain 5 or so mine able astroids. Astroids come in 2 types rock and planetary cores.
8. I think the stuff should be moving and better graphics.
9. Dwarf planets r usually ice, but there is one that is rock. The rock version seems to be smaller.
10. To be realistic a gas giant doesn't actually move around a star. It's closer to a common center of mass with the gas giant and the star. Gas giants r sometimes r capable of leaving the solar system while the other planets orbit around the star.
11. Duel planets I have only 2 examples Pluto and 3 other objects. The other one is the moon one day will move far enough out that the center of mass won't be the earth, but instead the moon and the earth will rotate aeound a center of mass that will rotate around the sun.
12. Lets not forget that there is solar rays and stellar rays. Solar rays r made up of subatomic particles, hydrogen, and helium.
13. The inner part of the solar system is in a dust cloud.
14. Black holes come in any range of sizes. Pulsar coming out of a young black hole. It is possible for a solar system to orbit around a black hole like they do around the sun or a black hole to enter a solar system.
Techyon streams or nebulas this is the only stuff I pulled from Star trek.
16. Solar flares and super novas, and exploding black holes.
This would be really accurate based on our current Nasa or anybody elses project. This is probably not comprehensive there is probably stuff I don't know about.