Oh my, I don't think you know how pleased my inner game designer is that the protagonist actually tilts their body when they are moving up or down the hills. It's such a small detail, but it definitely seen when you don't do it.
I'm so curious, how did you make the player? It looks like 2D Unity, but I don't know if the art is tricking me, it feels like 3D as well.
Speaking of art, it's beautiful. From a first look, it looks simplistic, but once you look closer you realize the detail that's put in and how well it fits with the area. The colors chosen, the way the lights hit each area. I thought I was just playing one of those indie classics at some point.
The story was heartwarming, and I'm so curious on what the "lost world" is.
I didn't run into some of the bugs that others did, I even tried to replicate them to see if it was just one area or multiple. Really the only thing I caught was this:
I tried to cut it as much as possible, so I didn't ruin it for anyone else who was playing. But, I think it's suppose to be "Some part of me always knew that", given the context. (Though my google doc keeps trying to correct it to "knows" instead).
As the others said, given the time frame, I'm amazed how well this was done. It's easy to tell you put a lot of love and hard work in.
I look forward to seeing what else you do.