Limitless possibility
I love this app and could sit there for hours trying to make different types of solar systems. It takes a while to get used to the gravity to actually create stable orbits, but once you figure it out, youll love it that much more. As other users have said, add more features(black holes, stars that move as well, perhaps ability to select a type f solar system and have it pre-made in a stable orbit) and even make it a pro version that you pay for all the extra goodies. Ill pay do it and Im sure many others would too
PsychoEmperor about
Planet simulation, v2.0