Ground Control/YMMV

In Ground Control

 * Complete Monster: Major Thomas
 * Moral Event Horizon: Major Thomas destroying the medical facility whose occupants already waved a white flag at the beginning of battle.

In Ground Control II

 * Most Annoying Sound: Your units have a habit of announcing every single instance of damage they take. And then there's "We're losing a victory location! We've lost a victory location!"
 * That One Level: Several missions stand out as being much harder than the others. Missions 23 and 24 are particularly murderous.