Stop doing spam. Even if 15.000 users add their names to the list that won't happen if some characteristics aren't.
http://www.kongregate.com/developer_center/docs/kongregate-api
I like the graphics, I should add unique skills for both characters in the prequel, like Fireboy: is Faster and Watergirl: can jump highter. I think this game deserves a 4/5
There lot of bugs while travelling: NaN Kilometers (Infinite routes and you CAN'T arrive to the city) and if you attack the castle and click "Go" You start to push the castle.
Its really awesome how everyone gives rates under 3/5 because of silly reasons like: "I want to jump over enemies to kill them D:", "The graphics are good but the music is bad","This game sucks?" Duh, Did sonny have that kind of feature? - Do you know that there is a Mute button right? - How many games have you done? - Geez... 3.11 ...
Make the boy's movement a bit faster, when you get hit by a moster you're done, they attack too quickly and/or your life is too weak for their attacks. 3/5 for your effort.
You should add to this game a progression -> If you are high, the rectangles would be smaller. Plus you can speed up the firsts rectangles that you are gonna use to jump.