I really like the theme of the game! I love the sprite of the little wizard I think it really cute and I also really like the how it collects gems! It all fits really well into the theme.
I think it would be helpful or useful to have a score ui, so we can keep track of how many gems we have collected. In addition, at some points I had some trouble jumping and moving forward at the same time which sometimes made it challenging to jump onto platforms above the ground platform.
But overall, well done! I loved the theme and the sprites!