th only way I found to get the 500+ power is aftergetting all the velocity items to the max is start breaking a lot of things to increase my technology a lot
this game depends mostly on how close to your castle your fighting. If you fight close you win, that simple. If you make an army with slow tanks and ranged units you win
It's quite strange, maybe it's a browser issue; try to close and re open your browser, or maybe try to use another (maybe firefox).