Jeej, just won the elite campaign, takes a lot of time to complete all three.
I make first 3 oil rigs, then one thunder globe and then only freezin rays. Completed all levels so except the last, there I made 2 oils and then just spam as lot buildings as you can, isn't so hard with all upgrades ;-). When you start next campaign, you ca't recognise your gun, soooo slow :P
 "Space is Key"){kind=icon}
 "Balloon Invasion"){kind=icon}
 "Sonny"){kind=icon}
 "Reactance"){kind=icon}
 "Tower of Greed"){kind=icon}
 "Gravitee Wars"){kind=icon}