I definitely see an overall improvement in your skills with your newest game. Ranging from the slick smooth animation and art, though pixelated, doesn't remove the clear cut details that are shown with each singular pixel on the screen. The music fits well with the combat as it builds up and dies down between each checkpoint.
Lastly is the game play which has a much more unique and most importantly, strategic element to it which forces the player to carefully utilize the orbs to their advantage or be killed by them. The enemies as well are a very nice touch getting steadily more difficult each time while having their own unique characteristics and challenges which though can be easily handled individually are irksome in number.
If there was anything missing I would say is some background art to add some atmosphere to the game. Perhaps a boss battle as well (assuming you had the time) and maybe a little animation when the frog guy attacks instead of him standing in place.
But like I said above, a really great improvement on last time and hope to see more of your talent in the future :)