BUGS: ;-) it happens single enemies just pass off the screen or towers stops shooting, very rare and I'm not sure if it is not because of version of flash installed. It happened twice for me.
one more thing: with cannons it is good to speed up enemies and kill them with meteors in addition. with other towers it is better to wait and use speed up when no other enemies and reinforcements cast.
It is possible to get all perfect plays putting all points to archer or mage tower and then to meteor/reinforcement. With mage you should use lots of towers to slow down enemies later in the game. For archer you should get 1 with Wrath of the Forest in a place surrounded by paths and use musketeer with one shot between it and exit/enter(s). Most of the time no need to use any other type of tower to win. Meteor have to be at least lvl 2 before putting points to reinforcements.
to mhoffer: have you watched strategy from help? I made everything but with some tips from movies. My feeling for strengths/weaknesses of towers is not so deep...
to: Kraagesh, vez'nan is easy to kill with barbarians. ~1 paladin/2 barbarians. paladins dead but barbs are ranged. he was not able to get to cemetary with 3 new barracks on his way just for him.
for easier play:
http://chat.kongregate.com/gamez/0006/1112/live/shootem.swf
link from "more information" about Media on this page.
be warned no badges will be reported but you can get them later opening save from this page.
To easilly get "ROYAL MAIL" achievement (and following):
RUDDER CONTROL + cheap flight duration without any engine. keep close to ground and use windmils + gold stars (HURRICANE necessery for later levels).
To get EASY GLIDING:
do not use any fuel till you get achievement.
for easy money:
all Duration achievement are easy to get with speed booster.
when you first meet it turn off engine and use fuel only to stay exactly above an arrow of speed booster.
 "Kingdom Rush"){kind=icon}
 "Elona Shooter"){kind=icon}
 "Flight"){kind=icon}
 "IntoSpace!"){kind=icon}