hello I tried your game and there were some things I liked but it is also quite confusing. I think you are trying to do too much with the shift key. most platform games vary jumping based on how long you hold down the jump key maybe you could implement that. I like the way that the standard attack doesn't work on certain enemies, maybe it would be good if there was a visual cue to show this. eg they have a shield and perform a counter-attack.
It looks good though and I like the sound effects BUT THE TV IS TOO LOUD :)