It says in the instructions, you try to take the earth to the sun without losing it or having it be destroyed by enemies. Maybe it should have been clearer, sorry.
No worries! I played it again knowing that and I get it the point of the laser sword, wish I could destroy the asteroids with it. I will say that walkway is looooong, and I don't know if I made it to the end or if my planet got destroyed without me knowing it, but it just reset me. Is there a win condition? The laser gun sword is a really nice model and the intro is top notch!