I want to comment on the controls.
With how dynamic flash games are, the tutorial should instruct the player using his configuration instead of saying "press default key to attack." Having to ignore the on-screen instructions and remembering what configuration I just set for a game I'd never before played threw me off a bit. (It's also a good idea to display the current configuration in the option menu.)
A control configuration should be included in the pause menu. It sucks having to quit and restart the game if you decide you should change the controls.
How come you won't let me use the Num Pad keys for movement? I'm cursed with a "compact" keboard that saves a whole inch of space by having microscopic arrow keys, so I use the Num Pad instead. But, whether NumLock is toggled off or on, trying to map movement to the Num Pad simply mapped the commands to the number keys that run across the top of the keyboard.
Directional positioning is too "sticky": If I attack while facing right, and my enemy jumps behind me, I'll press and hold left and continue to hit the attack key. But instead of attacking to the left, my fighter will keep attacking to the right, even though I'm pressing left.
Sometimes when taking hits while facing my enemy, I'll return the attack, without pressing any movement keys, only to find that I'm suddenly facing the opposite direction, thus attacking in the wrong direction and putting my self in a vulnerable state.