I got 5+ mill, I do have a life so as I quit after. I'm sure I can get more. Like sourwhatup2 my strat was simple and stupid. Tank (obiously), golden gun(obiously). The key is to spam nukes, littlerally just spam it the whole time. When u slow down to about the middle of the screen shoot the turtle with your golden gun it'll get you to the front. Oh and buy the chest bomb a little insurance against one of those pesky sky mines. This strat should get you the 3 mill achieve in a few attempts on kongregate if you play there no problem.
A good strat preaty much guarentees you arund 3 mill anything past that is preaty much random luck. I'm preaty impressed with the people getting 20+ and even 40 mill. The reason is because after 3 mill it's about a 50-50 to get every aditional mill. So to get something crazy like 40 mill it'll be about 2^37 or around 1 in a hundred billion, give or take a error factor of a couple digits =P. Which means: A. they have no life B. they are the luckiest toss the turtle players in the world C. A & B D. they are lying *GASP* E. I'm a retard and they have a even better strat (please share) e-mail me at shiangchen@hotmail.com