Hard Mode: 196,026 - 1 credit, from the beginning, ended mid-Journey 2, without success trying to break into Journey X
Normal Mode: 500,712 - 1 credit, from the beginning, ended a minute or two into Journey 4, without trying to break into Journey X
My goals which made me start playing again: Hard Mode, pass Journey 1 on 1 credit; Normal Mode, beat Alfred's score. After finally surpassing his score on a good run, I just continued that run and then set a new goal: break 500,000. Just barely did so before running Newton smack into a group of flying onions. At this point, I have 16 credits available, or 5 more than when I started playing again yesterday.
Also, the reason the iOS version of the game (which I recently test drove) is easier is that two of the touch control options, the ones which follow your finger movement, let you move Newton quickly around the screen. So, you can evade enemy fire more easily.