yah gotta hit the grass planet first.
i recommend going for the energy to health buff if you can also the instant recharger
my most potent build is pierce + multi-shot + reload speed it clears so well.
For starting planets super dont go the red one first its a death sentence
EDIT: to move to each planet you need uranium. However you can move ONCE without it after that its instant game over. (You spawn with 2)