Immortal Defense/YMMV

• Crowning Music of Awesome - The soundtrack varies between eerie, ethereal and heartpumping tracks randomnly chosen for the main stages, and kicks it up a notch for the act finales. The last standard level of the game has an entirely unique, twelve minute-long piece added in a patch. And then the final secret stage uses the achingly sad title screen music to full effect.
• Demonic Spiders:
  • Triad Flash enemies. Any hit dealing over 10% of their health causes them to become intangible and invincible for a moment, allowing them to zip through your defensive chokepoints and right into the goal. Worst part is? They're immune to the one tower you THINK would be the most useful against them, Circuit Points.
  • Those accursed ":P" enemies. They are completely invincible as their default state, and only become vulnerable for brief points while their shields recharge. Thankfully, they don't usually have much health, but they can easily slip through your defenses if you don't keep an eye on them.
• Goddamned Bats - In the final campaign area, you get accosted by these little flying... things that look like the love child of a Fairy Princess, Cthulhu, and one of those fancy plasma globes. They can't be destroyed or even targeted, and just love to come in and suck the power right out of your points...
• Moral Event Horizon - In exchange for not attacking his homeworld of Oss, Aa allows the second Bavakh brother to murder your entire planet. "Your planet burned today... But why do you still live?"
• Tear Jerker - Your betrayal of Corybantes in order to please the voices in your head. "God, Great Star...I loved you so much!"
  • Also, discovering in the final campaign that Corybantes' attempts to form a peaceful republic were for naught, as they've become an oppressive empire once again.
• That One Boss - Most people seem to have trouble fighting the Panopticon. Understandable, since it's Nigh Invulnerable to begin with and quickly forms an extremely potent shield that blocks all incoming bullets.
• True Art Is Incomprehensible - Did we mention that things only get weirder once you beat the bonus level? Yeah...