Thank you for the feedback! I'm glad you like it!
-The problem with the checkpoints is that there are not many levels and the checkpoints stay every two of them in general. If there will be a checkpoint on the each level it will have no challenge to the player. May be there is one place where I will make a checkpoint but i guess it will be only one.
-Flying enemies. The best way to beat them is using sword (also it have upper attack).
-I needed to give the magic wings during the playthrough instead of the beginning :D