Strictly speaking, not to completion. Like most of the people who actually finished the game, I downloaded a savegame just past the EPIC jumping puzzle / escort the brainless friendly (NOT) / timed mission penultimate stage. The actual final boss was no worse than the tanks.

What went through that idiot designer's head? "What's worse than finding a worm in an apple? Finding half a worm in an apple." And then it goes on to one of the best endings ever. What a git. The final boss makes you want to pull out your short hairs. No, but wait, "the rest of the game was great though." Yeah, deleting this one was the best decision I've made this year so far. Starts out sucking... gets worse... final boss give you piles... ending sucks rocks. But apart from that, Mrs. Kennedy, how was the parade?

You almost got it. Thing is when boss appears above you, you don't attack him but dodge his attack. After that boss will appear aside you and after three or four hits it will be done.

I suppose this stage is only reason why there is dodge move at all.

Also you can use second set of controls (SettingsApplication) to handle inversion. I'm used R - down, F - up, G - left; and just slide hand right when inversion happens.