Creative...
This game is definitly unique to say the least; But I do like the idea behind this game! Here are a few suggestions and facts I have to make the game more realistic.
1) Not all galaxies are elliptical in shape; some are spiral (in both directions), some are more like a bar, some are like a giant ball and then some galaxies have no real definitive shape, they are just blobs.
2)Maybe you could add in a way to collide to galaxies
3) If you really like this subject, why not show the formation of stars or make a game where you build stars.
4) Finaly; galaxies can have stars of all sizes, not just small or large. I am certain that somewhere online you could find a statistical breakdown of the sizes of stars.
Hope at least some of these ideas were useful and that you make another!
p.s. If you need any help with data or researching galaxies let me know ok?