Flash Empires
 

My high score was 1839. The soldiers that cost 50 gold at first will work, but even the pacman guy won't stand a chance around wave 25 and up. Towers...towers...towers. Upgrades probably too, but I didn't use any of those. Might have gotten further with them.

http://www.addictinggames.com/flashempires.html

i got really bored so let them kill me at level 40. It'd be better if the levels went faster. That and if you upgraded things they stayed upgraded!