Answer:
I am a box that holds keys without locks, yet they can unlock your soul.
What's a place you have left but didn't enter?
I'm not man's best friend, I'm their enemy, I can mark your end, yet you do not see me, I am very small, but very tough, If you have me, then you have it rough.
What word starts with 'E', ends with 'E', but only has one letter? It is not the letter 'E'.
It flies when it's on and floats coming off.
I can only be played on a windy day
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?