I really like your game. I think the animations are well done, and I like the second level's difficulty. It was fun having to explore downwards rather than up or across. 

The sprite animations are really well done, I like the skull rotating, the character has a lot of personality and the bats are a cool design. The bat detail is a bit hard to make out, I would make the eyes or other details a bit brighter so they stand out more. I really like the below ground areas in the second level, that adds a nice reward for exploration. The design of the horizontal moving enemy is a little less clear, they kind of look like flamingos, but they also have a component that looks more like machinery, are the robot flamingos?

The spinning skull collectable is cool. The jump in difficulty from the first level to the second level was rather sharp. movement is a little fast for the single block platforming required to drop down the pit to collect the first skull in the second level. The Background sets a nice tone, but causes the flying enemies to be difficult to see.  I like the theming overall, has a little of the ghosts and goblins vibe.