Firstly, I wasn't paying attention when I got this game and ended up getting the full version instead of the trial. Now, I don't really like this game (I'll admit: it's a little fun on the highest difficulty), but I'll share with you what I've figured out.
The points are really very easy to get. Don't be fooled by that 10 million point achievement. I'm #13 in the world with 110 million big ones, and I never made it to wave 20 in that session.

This is the secret I found to banking it big in this game:
Before you begin a game,
set your difficulty to 10. From the first level that you get enemies,
do nothing but shoot the enemies. Do not touch
ANY crystals. Once you've killed them all and no more are coming through the gates, grab
one crystal. This triggers the enemies to begin entering through the gates again. Once you've killed this new set, grab just one more crystal and repeat this process until there are no more crystals to get. Enemies will not enter the level after you get the last crystal.
Never shoot the gates because you may accidentally shoot a large crystal. On difficulty of 5, large crystals are worth ~50k max. On difficulty of 10, those same large crystals are worth ~1.1 million max. Using my method of shooting the maximum number of enemies on a level and grabbing the large crystals every chance you get, you can have your 10 miilion point achievement by wave 4 or 5 depending on how often those large crystals make an appearance.
When you get to wave 10, you'll earn lots of points because those pink globules are worth 50,000. For every respawn, the level averages about 20 globules. 20 x 50k = 1 million even. There are about 25 - 50 crystals in that wave. You do the math.
Note: If you die in a batch of enemies, you do not need to get a crystal to make more appear. They'll enter through the gates as if you grabbed a crystal. Also, at difficulty of 10, everything that you touch that gives you a warning on lower difficulties will kill you instantly (e.g., level mines, the exit, enemies' mines, etc.). Also,
smart bombs will destroy large crystals.
Some enemies you need to be cautious of:
Turtleshells: They shoot fast and often, and they have good range. They usually bundle up to make you dance like Michael J. Fox in
Back to the Future Part 3.
Starfish: Just when you think they've slowed down and start moving away from you, they hurl themselves very quickly at you. On difficulty of 10, you need to shoot those bastards like you're earth's last hope.
Spinners: Don't shoot these guys at close range because once you do, shrapnel flies in every direction. It's best to holster your weapon as long as you can until you've collected enough crystals then use a smart bomb. I sped through levels with spinners like a madman. I wasn't even after points, just survival.
Mine-layers: They lay mines that look like crystals with a black dot in the center. These are the other guys I speed through. On difficulty of 10, there are a lot of them and they lay mines quicker than you can imagine. Smart bomb their mines after you've shot as many of them as you could.
Those molecule-looking green/red things: It seems to me that they predict the path that you're about to take and shoot at it.
Those boxes that momentarily equip laser-lances from two sides at once: Their reach is pretty far considering the little room you have to maneuver in while avoiding crystals, mines and other enemies in those higher waves.
The left-right/up-down green squares: These guys are easy to avoid. Shoot them to stop them from moving for a few seconds. On the highest difficulty, there are a lot of them and they travel fast.
It's bedlam when you have several of these guys bunched together in a level and you're trying not to get crystals so you can get that high score.
I go about this game in a frenzy. I try to do things very quickly. That's why I've shot up tons of large crystals and died stupid deaths.
Questions?
This post has been edited by metaldevil: Feb 10 2006, 04:31 AM