I like your theme!
I like the main colours you used "Black, White, Gold, Red" plus the simple shapes used, as it fits nicely with the other game characters. Because if it was too sophisticated, it would look out of place and it wouldn't look neat.
I especially like the in game features, such as the gems and runes!
But I do say that the top hat is a bit tall XD. Another suggestion might be to change the coins into crystals, because the other character designs have crystals.
I hope my advice has been helpful to you, and keep up the GREAT work! :D

My favorite so far