How does saving / checkpoints work? I'm assuming the game is a couple hours? thanks

...how's it going?

I have an issue with my save file. I did the first level of the ice world, died, somehow was able to skip to the spooky world, and after dying in that first level I can't play my save file anymore. Here's a video of the whole thing occurring: https://www.twitch.tv/videos/1468119055...

all in the title, don't have much more info to add, sorry, will keep an eye out for whatever is causing it

I find the difficulty to be fine but it would helpful if there were some modifiers. For instance, if you could slow the speed of the enemies down...