so i beat the entire game using the first gun i bought which was the p30 for $1,000. and i agree with those saying defense mode could be better. maybe some bosses or more varied enemy types. when i fifnished the game i bought the saw and was so bored on defense mode... i don't even think an enemy made it all the way out of the box til wave 16, and doing the elite's over and over was quicker to get money anyways (i wasn't about to go past wave 20 with nothing to hold my attention..... maybe add bonuses that fall and u have to shoot before they touch the ground? faster enemy spawn? idk...)
to get the lvl 17 challenge kill all the enemies but one. he has to have a pistol and u need the anti bullet field equipped. then just dash through the bullets and jump immediately away til u get the untouchable achievement :)
.... so i downloaded a puzzle solver and when i was trying to arrange the puzzle so i could tell the solver what the current numerical value of the pieces were I.... I.... I accidentally solved it :_( i hate them
 "Effing Worms"){kind=icon}
 "Escape #5: The Freezer"){kind=icon}
 "The Gun Game 2"){kind=icon}
 "Necronator"){kind=icon}
 "The Final Death Wish"){kind=icon}
 "Rings"){kind=icon}
 "Robot Wants Puppy"){kind=icon}
 "Sift Heads World Act 1"){kind=icon}
 "ClueSweeper"){kind=icon}
 "St. Pattack"){kind=icon}
 "Geo Land: The Dream Traveller"){kind=icon}
 "The Great Massacre"){kind=icon}