I'm using Construct 3, which makes it really easy to do the lighting. You just set up the walls as having the shadow casting behavior and then have a shadow light that moves to follow your player's movement. Built-in stuff like this is what really sold me on Construct after using Phaser & Unity for a while. Hopefully your game framework has something similar!
Construct 3 also makes it really easy to set up a parallax layer like I did for the stars.
Regarding the sword and bug-freeness, I wanted to have an animation happen when you pick up the sword that shows the player jumping up and down holding the sword, but I couldn't get that one to work for some reason. Maybe I'll revisit this sometime and fix it. 😆