I think you've got a memory leak in there. Using Iron (Chomium) at low quality setting with latest Flash. Usage moves up to and up. Initial usage of about 48Mb gone up to 280Mb after some hours, until the slowdown was annoying enough to restart the browser.
i managed to build a snake maze. like that: 3-3-4-5-6-7-10-7-6-5-4-3. this way they followed the road. managed to kill over 1700.
but the game turns into pause-repair-continue cycle. to the end the cycle was shorter than 1 sec. i seriously doubt anyone can get past 2000, or near it.
while building a maze: leave some places in the maze for the slowing towers. build many short turns as the towers need a lot of time to acquire a target.
after building a maze: 1. upgrade one 10g tower to max, then build 2 splash towers, upgrade both to the max. build slowing towers in between. don't upgrade them. after splash towers, build only boss towers; 3-4 of them, then upgrade gradually.
tip for easy win: build two paths, one very short and one very long. close the short path by blocking the exit point with a tower. if the creeps are closing on the exit, open the short path by selling the blocking tower and block the long path with a new tower. the creeps will have to o through the long path back and into the short one. repeat, if the creeps aren't dead.
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