I don't know who that undead camel guy was,..
he was one page before me and can't beat level _3_! i can't beat the last one, and i have MEMORIZED this game! like every six levels there's fraggers, every 7 levels there's air, and every 8 levels there's tough crap, not to metnion that on level 1, instead of air on level 7, you get spiders (big) and every other level you get air on 7, and level 6 would be hard enough, but did you reallly have to increase everythings health by 150%? (ithinknot!) i mean, dude, WTF? i have a battery of FOUR MAX LEVEL SAMS and i can't kill the 42's, even past that i have an entire hallway built of blue vulcans (less range, better rate of fire) and my grampa keeps using a CHEAT: you build like a long maxe with 2 exits, you block one, and unblock the other when crap gets to far, i personally don't do this because i find it cheap, ineffective, and cowerdice, so i just eat it like a man. but for groups of enemies up to about 40, MAX LEVEL SAMs do the trick, and i use a special patern for my DCA's too, i keep them upgraded, thoroughly, and have like abox shape minus the lower-left corner and the upper right...
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* like this illistration shoes, and you should try to build as complex a maze as you can too., like this other tactic i have, you build a giant swirly pattern and then in the middle i have a top level vulcan so it gets best use out of its potential. and then as you get funds, you upgrade all its neighborring turret s to red too, the ruslt: a giant sniper army with ALL its range potential used.