Z-Warp (HP)

If anyone is struggling to score 500,000 points in easy mode, I would recommend playing on a higher difficulty. I was able to achieve this by making it to the boss on level 2 on hardcore difficulty. On easy mode and normal I always died at the Acid Reflux boss (3rd level). If you run out of lives and need to use a continue, your score resets to zero. The higher difficulties do add more bullets and change patterns of bosses a bit, but you wont need to progress as far.

* Another important note is that you can fly over top of the bosses without taking damage. Acid Reflux is particularly difficult to avoid bullets from the bottom of the screen without utilizing flying high on the screen.