Don't be shy!
But that's in my personality!
Anyway, for bosses I'd say try avoiding the mess that was the Skeleton King. Too many enemies throwing things and slowing down the game (the server may be able to handle it now, but some CPUs and GPUs can't).
Also, I think the bosses should move a bit more then they used to. Maybe they'll try to dodge attacks or follow you too close and keep you on your toes (fingers?).
One more thing: a life bar. It doesn't have to be on every enemy, but at least on the boss (you know, like Mega Man).
Nice Job! You really put your time in effort into this.
@AK these are for GM's only and won't be accessible to the public.
We're aware of the dangers of cheaters/hackers in-game, and we're currently going with a hybrid approach that is more naive towards player's data being sent to the server but with a lot better performance. We don't want to waste all our energy on those few cheaters anymore as it's just not worth it, especially as we're a co-op game. However we will implement anti-cheat measures where possible.