quindraco, when you move from the box to the button, make sure that you move across the menu. The button will stop being lit up if your cursor goes off the menu before you get to the button.
I did it by letting interest pile up for a few levels about midway, then building craploads of manticore and elemental nests around gyms. My points were mostly spent on manticores and traps, I think.
This is an interesting experiment in a different style of firing control. But it's not a good game. Too basic, without any effort at visual or audio design.