A pretty nice game, with some decent graphics, sound and concept :)
I can't quite understand what I do to attack and what I do to double-jump, because it kind of feels as though it's random. It controls very nicely and is quite responsive. I think it would be nice if there were different animations for when you jump, double-jump, attack and take damage, but with the background and the nice sprites that isn't exactly necessary :)
All in all it's quite fun and you could play it for a couple of minutes. It could do with seperate input for attack and jump, but it's perfectly playable and quite enjoyable in its current state :)