I liked it. I think the story was fine. I had a pretty good idea of what she was looking for by the end.
There's grass on layer 3 @ x999y1002. It's on the save point which causes a swim after spawning. I saw no other errors.
I missed the yellow key, but it isn't necessary to reach the end. I don't know if that is intentional or not. Is there a yellow key?
I liked it too! The umbrella ride while the chasers are after you was a bit tricky but fun.
I checked the level editor and there wasn't a yellow key
Good work. Keep it up!