when you press enter, you hear the poerup sound and then a hum. this means it's active. when enemies come close to landing, it will destroy them instead of making them land. it takes approx. 50 seconds to recharge afterwoods.
also: i'm stuck for ideas on trophies. i have 22. what now? i don't have any more ideas.

I'd also love to know how to get those!  I've only gotten one trophy (spelling?) and don't quite know how I did it.  Also what about getting the secret weapon?  And when you do get it, is it permanently unlocked for all future games, or just for the one game you're playing?

Hi again,
I'd love to know how to unlock the secret weapon.  I now have three trofys.  I can't sware by this, but I think I might have figured out where the trofy data about trofys earned is stored on the hard drive.  If anybody wants details let me know.  Of course this might also contain the product registration too, I can't really tell.  Anybody wanna share any other tips?  If you want to do so privately I will provide my Email address.  It is scrambled so spam bots can't get it, but just remove the letters q z and x from my address to get the real thing.
[email protected]

Morgan Kane. how did you unlock the secret weapon?

hi,
where is the trofy data?

and the weapon?

oh
anyone else know how?

I have just verified the data file.  I won't give away the exact filename, but here are some hints which should lead you down the right path.
Look in the directory where the game is installed.  There are several subdirectories containing sound files in what I assume to be a proprietary file format to keep us from discovering the game's secrets by simply listening to the sounds.  There aren't many files in the main directory though.  Look for a filename that might contain what you want.
Note.  The contents of this file is *not* human readable.  This file would appear to contain all data related to earned trophies, scores, probably even unlockables and the like.  It does not appear to contain the product ID or unlock code for registration purposes.  It is unknown whether this file is keyed to the particular product ID/unlock code combination, or whether such files could be swaped from one computer/user to another, thus giving any person with access to the file all the stuff earned by the original player.

On a related subject to this, I've not yet managed to beat the game, even on Easy!  I can get through the first ten levels pretty good by just holding down the trigger and moving about, thus destroying enemy craft rather quickly in some cases.  The boss's first challenge isn't really one, especially if you've followed the above advice and have plenty nukes and rockets left.  But I have yet to get past the satellite.  How the heck do you beat this thing?  And, once you do, how hard is it to beat the boss himself, and do people have any good strategies for beating these guys?

not true. not true at all. to get the cheats you need 10 trophies.
about beating the saterlite, wait at theleft side of the screen, and then when he is in the centre of your headphones/spekaers fire. watch out, about 3rd time passing you will be right under the laser, best thing to do is to move away at just the right time. t's quite hard to exxplain.
the boss isn't really that hard.
by the way,  iwouldn't recogmend holding down the trigger. get good accuracy. therer may, just may, be a trophy installed.
and if your good enough, beat easy without using any rockets or nukes.

Well you obviously don't need to beat it on all three difficulty levels, 'cuz I have yet to even reach the boss on Hard.
  The satelite can be tricky. It moves back and forth and fires off its laser at intervals of a few seconds. It's quite powerful, so get out of the way when you hear it charging up. Then just get the thing in the center of your speakers and shoot it. Don't hold down the trigger though if you can help it. As I understand it there is a reward for high accuracy, possibly that Sharpshooter trophy?
  As for the commander himself, he can be tricky. He flies around in a ship and releases nukes. Like the satelite laser, these are quite powerful. One alone can do considerable damage. I'm told you can shoot them but I've always been too busy avoiding them to try. Anyway, center the sound of the ship in the speakers and fire. Enough shots will bring it down.

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All the secret items in the game are unlocked when you earn a certain number of trophies.

The satellite and boss are very easy.  For beating the satellite, I find it easiest to sit in the middle of the screen and fire off a shot or too when he flies buy (similar to the orange ships in alien outback).  Just follow the boss with the trigger held; he shoots nukes before flying away, so they should be in your path most of the time (you'll end up hitting them anyway).  This won't screw up your accuracy if you were careful for the normal levels.

Speaking as a member of the test team, a lot of the trophies are obscure (and one or two are totally pointless) but you can get around 20 by playing the game with as many extreme scenarios as you can think of (you/enemies health low, ending game with high or low marks in this or that, difficulties etc).  Bonus games are by far the easiest way of earning trophies.