Sketch for Box Cover ~ Emily Marsh

Here's a sketch for my game cover. There's my underwater castle on the left, and on the right is a bubble that is holding a land scene, showing how parts of the game are above water. I was considering adding more of these landscapes in some of the other bubbles. What do you think? Does this work for the cover?

Also, here's my vague idea of the plot as of now: The underwater princess hero finds a magical harpoon that allows her to leave her underwater world, and transform into a creature with legs. After exploring on land one day, she returns to see her castle abandoned/destroyed and she has to explore above water to find her family and rescue her world. One challenge for her is that to attack, she throws the harpoon (which she can usually retrieve) but when she's not touching it, she loses her ability to change forms.