I would work on balancing the audio levels for the piano's hit, it has a real sharp hit to it and it keeps the listener from really getting into the song, kind of like a constant ticking noise in your ear.

Getting an age of empires vibe from the note progression!

I really like the cell shading in combination with the thicker lines, reminds me of a pixiv artist by the name of chico which i always loved.

Use the Adult tag please.