I kinda wish your health refilled when you level up but I would understand if it didn't. Team comp doesn't really seem to matter at all, and like Magbo said I have no idea what shadow does. My assumption was that it would make you invisible to enemies but directly after using it the ronin cat was brutally murdered, so who knows.
Anyway I really like it! The music/sounds can be a bit grating at times but overall it was a fun little tech demo. Keep it up, this has potential!