Good classic platformer. Some constructive feedback:
The Good:
1. Nice art and pallette. I love the way you change completely after each level
2. Music is SFX are also good
3. Enemies , moving platforms and diamond locations are very good.
What can be improved in my opinion:
1. Jumping needs some fixing not to get stuck
2. I would give an indication on how a level ends
3. The ghost prefab that instantiates after you pick a diamond only shows once (maybe it a layer thingy)
4. The ghost prefab is not pixel art and does not compliment the style of the game.
Play my game if you like and give me your views and rate if you think it deserves it :)