I had a lot of fun with it by landing a guy on Duna (Mars basically). But then I felt like I should rescue him, so ended up going on the even harder mission of

I had a lot of fun with it by landing a guy on Duna (Mars basically). But then I felt like I should rescue him, so ended up going on the even harder mission of bringing him back home, which required being able to land and then take off and make it back, as well as landing in a specific spot on the planet vs just landing anywhere.