I loved the sound track and the story. Now I want to write down the thing you should consider adding:
*Optimization: You should optimize your game a bit as it almost crashed on my pc. Though my pc is not high-end, it is medio, but most of the game run it smoothly. When I started your game, it was in black screen like 3 minutes, windows sending message about it wasnt responding. Music were on though. I got like 8-10fps atmost.
*Add a menu: A pause menu or an exit button to make it easier to quit.
*Buttons misplaced: When the game overs, the restart button appear half at the bottom of the screen.
*When the hero travel back to the past and was talking with lackie, they were still hurt by yhe enemy. You should make the game pause while showing dialogues.
Hope this will make your game better. Your art and sounds are awesome. I really loved them.
Tweak those small things, take your time, your game will be more adorable.