2.
As for power ups the blue speed and teal shrink
crystals are the most common, I prefer shrink over speed since
speed is worthless if you cant get around something, and shrink
gives you a good chance of fitting between shots. Tan rebuild
towers is pretty useless until the later levels but even then
may not be worth grabbing since when you get any new power up
you loose the one you are using. Purple extra life and orange
power shot are almost equal in rarity and worth. Power shot will
hit an enemy and then shoot from the enemy again so it can be
used to kill enemies almost twice as fast as normal, especially
when they are packed together. If you can try and get more than
one power shot at a time, because it will shoot off again for
each power shot that you have collected.
3.
Don�t worry too much about your towers, the object
of the game is not to save them after all, its to save you! You
can hide behind the towers from enemy fire but not power up
crystals, which is good and bad. Just be careful to not stay
beneath a power down even if a tower is between you.
