This game has a lot of trouble with sluggish/unresponsive controls. It doesn't seem to have a consistent framerate either, it's quite jumpy. Also right now I'm stuck on a plain white screen after dying on a boss? Nice ideas, but needs a lot more technical polish.
The ever-increasing lag and tendency for levels not to reset properly make the game a lot harder than it should be. I'd died about 10 times in levels 1-19 and about 80 times in level 20, let's see what it's like from there.
I don't like the controls not being listed in-game. I also don't like the camera being centered between where my cursor and character are; that means moving the cursor moves the map and not just the cursor which is bad for aiming.
Thanks for making earlier levels a bit easier. The game could use an across-the-board slight speed increase I think (maybe implemented by making the distance between castles shorter rather than increasing attack or move speeds), and killing the enemy's castle should also end the battle immediately even if he has units left.
You should add in-game instructions. Even something as simple as "Don't touch anything!" would be cool. Also I died in the first half a second or so my first time, maybe start with just one ball and add more balls as the game goes, or start with the area bigger and make it smaller over time. Also, once I die, there's no "You died! Final score: xxx" screen and there really should be; the game should also track my personal best score so I can see how I did compared to that.