Simple planes has no ceiling.. This is where simple rockets could continue. I imagine a campaign that would involve delivering a package to Mars..... designing road transportation that would launch an aircraft that would carry a rocket to 40,000ft then would launch to Mars... ... Upon reaching Mars it would release a plane which would respond to the Martian weather and gravity to deliver the package to Mars 101 airstrip. Different conditions for each planet and moon. There is a clear continuation to the ceiling on simple planes and I feel simple rockets would fit in nicely. This could be epic!