I really don't like that you can't redo previous levels. This makes the difficulty of the game very unforgiving. You have to get perfect in every level and know exactly what upgrades to get when in order to have a fun time in this game. Because of that I'm giving this game a low score. If that was fixed then the aiming would be forgiven and this game would have a chance to win the week.
Please vote your conscience. :) We're working to fix the crazy speed issues.