Invasion Tactical Defense - addicting Flash game

Found this addicting Flash game last night.  It reminds me a lot of the old school Space Invaders for Atari.

Aliens are attacking and you have to protect your nuclear factory from being destroyed.  You have 6 gun platforms and several different weapons of varying firepower to fill them with.  After each round, you earn money for repairs, upgrades, etc.

My only complaint is that each round seems to take a long time.  The good thing is that you can leave it running in the background- it will pause at the end of each round.  This may not be good if you are supposed to actually do something while the aliens are attacking.  I know you can alter some settings on your guns.  It may be possible to do other things, but I haven’t figured that out yet.

I’ve made it through Round 6, but my first few games (the learning curve) I was only reaching 3-4.

Play Invasion Tactical Defense