Things I liked, you actually made a very smooth feeling game and I loved sliding around on the walls and throwing shurikins everywhere. The mechanic with calling back the shurikans took a bit to understand but afterwords I really enjoyed flying them around. I also felt like the sound and effects you had livened up the atmosphere and there are enough checkpoints strewn about to make the game not too too hard.
Things I didn't like, for some reason it felt very hard to dodge the enemy fire? While a simple solution on my end is to just go slower it feels weird to give the player all these tools to go fast with and then not reward them for doing so. In addition, the instant kill of the spikes felt too harsh and would act as a very sudden reset for a player who may have been enjoying just zooming through.
Overall though, I got to say I really have enjoyed your game and I hope you make many more!