Desktop Tower Defense FTW!!!

This is how I spent most of my day today (other than getting this site setup!) This free flash game reminds me of some of the user created maps I used to still play in StarCraft. You basically setup your weapons to take out the baddies, or "creeps" as the game calls them, as they walk across the playing field. There are multiple difficulty settings as well as "Challege Modes."
Each level, or 'wave', contains 20 creeps (10 in easy mode) and they arrive every 25 or so seconds. You cannot block the exits. Your only defense is to purchase Towers to attack them. Some waves have special abilities like FAST or FLYING. Also, after every 7th wave is a BOSS wave that is especially hard to kill. I made it to about the 5th boss or so.
Link to the game - Here
Instructions - Here
Secret Tips: Read the instructions! A highly upgraded tower does a lot more damage than many level 1 towers. Anti-air does what it says on the tin. You can earn a higher score by sending waves early, but be careful not to swamp your maze! 'N' sends the next level early.
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