Many thanks for your comment's :D. It woud be great if you could help me test the game before it's full release.
About the grandma's grave, there is another "epilogue cutscene" now in development that explains what happened to her, and Mu's motivation to explore the world. I'll make a new demo update when it is ready ;)
About the bouncy dogs, you just need to hold the jump button to bounce higher. If you do so near the center of the first dog, and keep going forward holding the jump button, the character should land on the other dogs without any problems... I know this level is kind of hard and that's because is the third (secret) level of the game. Since I haven't completed any other levels I had to include it in the demo. Also the bouncy dogs mechanic is explained in a previous level (not included in the demo) Maybe it wasn't a good idea to include this specific level on the demo :p. I apologize for that ^_^