A good game that was poorly executed. While you have a great and original concept, great art, and great music, it's really disappointing that some of your game play was lacking.
Your main issue is that the camera moves with Lucia. This makes it so that you can unintentionally move the light if you're holding on to it while moving. Since there are many levels where you need to have the light while you're moving, this is really annoying. Also, the fact that the light has a limited speed makes it so that your light just feels really clunky, especially in scenarios where you need to whip it towards you really fast. I can't really offer a solution to this, so I'll leave you to figure it out on your own.
Also, your levels are frustratingly difficult, probably because of the things said above. Once I got to the level with all the carts going sideways, I had to give up. The worst part was that I was blaming the game, rather than myself. If the player says "Oh man, that was so stupid of me," you're doing it right. Mistakes should feel like the player's fault.
One more thing, and this isn't as important. When you're creating a game, blend story with game play. There is nothing more boring than having to read through a wall of text before you can play the game. Trust me, hardly anyone is going to want to read through all that. Spoon feeding the story slowly into the player while they play the game is a great way for them to actually understand what is going on without them getting bored. If there's something you want them to know RIGHT NOW at the beginning of the game, for example, "Why is the light out?" just put it as your description. Although, shoving everything towards the player at the beginning of the game isn't that big of a deal in the first place.
No doubt you are faced with a big issue that is hard to fix because of the style of game you chose, so you can hardly be blamed for it, but it's an issue that should be fixed nonetheless. If you plan on creating a sequel to this game, fix this and you'll have an incredible game.