you should try the buy/rent gun system, but have a few free user weapons so people dont get angry at how price the get. base the money on points and dont only give one credit for a kill. that enrages so many people you couldnt belive.
it needs more levels. i beat it on an average of 5 to 10 minutes!!!!!! the "ready" button screws me up because i want to put something there and i cant without starting and loosing!!!!! Brolly123 is right. why wait an extra 5 to 10 seconds waiting for the evil meeter to get to play another level! press + if you agree... i bet you will. :p