I've made quite a lot of changes in the app since my last post, so you might want to check it again.
Most significant change is the addition of a "free flight mode", which allows to direct the spaceship's orbit manually. Also a tutorial to help to better understand the controls.

When you launch a spaceship from Earth to the Moon it should launch immediately, but for interplanetary trajectories you need a correct alignment of the planets before launch. You can see the countdown to launch at the upper right of the screen. Several people have asked me about this, so I will have to think something to make it more intuitive, perhaps putting the countdown in a different color to catch the user's attention.

Of course you can add it to the projects page 

I made this app using jPCT-AE. Not sure if I would call it a "game", as it doesn't involve any goal other than simulating the trajectories of planets and spaceships. The app is focused on realism rather than gameplay.

Here's a link to the free version:
https://play.google.com/store/apps/details?id=gpaw.projects.space.spaceflightLite

And here's the full version:
https://play.google.com/store/apps/details?id=gpaw.projects.space.spaceflight

Hope you enjoy it!