God Damnit, Cave Story

[Rainbow Dash]

First things first: If you spoil anything I'll kill you. Simple as that.

Now, I made an innocent decision by accident (again) that set me on the easy path (again), and now I have to play through from the beginning (again).

Again.

These arbitrary decisions that can ruin the game forever are really starting to get annoying, which is a shame because it's such a good game otherwise. Now that I'll be starting from the beginning again, it'd help if someone told me everything I need to avoid doing/do to stay on the hard path and the things that will change the ending.

I'd like it, though, if you could refrain from spoiling anything for me or others who may happen to read this thread. I would be very unhappy if you thoughtlessly spoiled anything. Very unhappy.