This game is mocking me!!
I have now tried this 5 times and got the following:
I don't understand how I could be getting worse at this challenge.
I am playing on easy, using the Magma weapon, I hit just about everything that appears and I kill them right away. I also grab the rings immediately. It's almost like the better your rank - the less rings you get. I think I am done with this challenge for now though. I may try it again when I unlock the 3rd ship. Just too frustrated to see the huge FAILED
logo pop up again.