Storm the House 3

Sparta achievement tactic: buy 3 quackers, upgrade one to maximum, and one to lvl2. Then buy 60 gunners. That's all. You can leave the game and go get a drink, they deal fine with spartans and get you a achievement. (notice the plus-sign to the right, for the good of all of us).

"Sir, considering how many men we have, couldn't we just take over the world or something?"
"Nah, I want this guy's house."

"Sir, his front is heavily armed and defended, but his flanks and rear are completely open." "ATTACK THE FRONT!"

@Alamodelatte: They're clearly after his infinite ammo supply box

ok, let's go over some not so obvious game mechanics.
Upgrading your gunmen doesn't work like most games. going from 1 to 2 shooters doesn't double the amount of shots fired. The game works with a timer, every x seconds a shot is fired if possible. every time you buy another gunman, it decreases this time a little bit. This has the effect of making the first 15 or so upgrades nearly identical to 1st upgrade. Around 20 or so, the upgrades hit a "critical" point and your gunmen become awesome. Upgrades continue to be awesome up to roughly 50 (i might be off). Alot of the other upgrades work with a similar mechanism, so try different things out.