Below is the icon set of planets I created for my app. I think all of them have their own characteristics and came out the way I wanted. I found creating them a little difficult as the curved shadow took a while for me to grasp how to smoothly create it. I did these icons initially on  white frame but decided to try black and a very dark grey as these two colours will more than likely be one of my background screen colours. I prefer them on the dark grey frame as its not just complete black and it think it will help bring out the icons more in the final screens.

Below is the icon set for the spaceship and the alien buddies. I really like how these came out. I think they are simple but effective to what I want my app to be. I think my app is going to look kind of retro by the time it’s done as the aliens are reminding of older space cartoons. I put them in three different colour backgrounds the same as I did with the planet icon set. I think they look best on the grey background, especially for the alien buddies, as you can see there little antennas on the grey, but on the black I have to change them to a light grey or a white, it’s a small detail, but I think they look out of place when they’re done white.