Space is an immensely huge location which is comprised of the space between physical masses. With respect to games the physics and scope of space are generally neglected or ignored, due to the limitations they would impose on the story and experience. Proper gravity rarely applies in videogames, and almost all space games feature sounds in the vacuum, a impossible phenomenon. Space can be divided into two obvious variations: Intrastellar and Interstellar space.
Intrastellar Space
Space, and then some.
The spatial area containing stellar masses including stars, planets, moons, gas clouds, asteroids, and other celestial bodies. This is the area of space most often included, and portrayed in video games due to its relative complexity compared to the rest of the universe. Some prominent uses of intrastellar space (both realistic and fanciful) are in games such as Super Mario Galaxy, or Descent: FreeSpace - The Great War.
Interstellar Space
Mass Effect 2 has a whole lotta space
The more neglected deviation of space, interstellar space is usually left out of games due to its immense scale and lack of much physical matter. Although it is BIG, it is also very empty.
Interstellar space is full of celestial objects, such objects include trillions upon trillions of stars, red and brown dwarfs, normal main sequence stars (such as The Sun), red giants, and the rare but well known hypergiants, black holes, nova, supernova and hypernova, star remnants such as neutron stars, and millions upon millions of Galaxies, all in our observable universe.
Space in Games
Interstellar space is a now common subject to some video games, Sins of a Solar Empire, Mass Effect, and the popular Star Wars series. Traversing interstellar space is usually tackled though use of hyperdrive or other such device in the context of a game's story, while it has also been thoroughly ignored though use of galactic maps or other such things in games as is demonstrated in Star Wars: Empire at War.