MAN! So many enemies! I feel like the worst guardian in the universe!
I like this game's concept and I understand you did not have much time... But if you're planning to launch another version, consider make things easier for the player. I suggest:
1 - Add difficulty option for the player (the actual could be the hardest);
2 - Increase a little the "contact area" of the sword;
3 - Don't make enemies come from underground - put them at least as high as the tree since the beginning.
4 - Tell the player he can double-jump. Sometimes we take time to discover by ourselves.
To make things more cool, I would add come extra image and sound effects for the "slash" of the sword. Also, while using the sword in the middle of a jump, I would decrease the gravity effect on the main character (retrieving it when user stopped slashing), so the player could make several sword movements in the air. That would be blasting awesome. Physics aside.
Great work, man. Keep on it.