The universe is huge, wide and big playground for the gravitation. This can be tried by one crew of your rocket that is trying to collect few things and get through all the levels.
I met Space Gravity Game thanks the sequel and another expansion. I was surprised with classical principles and that the simplicity can be so entertaining. In all the levels, you collect needed experience, fuel and money to improve you motor or tank. There is always some planet grabbing you with its gravity and you just hope you don’t run out of the fuel.