While it's just a cinematic trailer with a lot of fancy explosions, telekinetic energy and a few headshots, it still hints at a very important element that plays a major role in the upcoming expansion for XCOM: Base defense missions.
The trailer is exceptionally sleek and drives the point home that some of your personnel may not be as trustworthy as their paycheck you cut for them each month. The concept of betrayal while dealing with an alien invasion is pretty slick.
A few of my biggest gripes with XCOM: Enemy Unknown had to do with features that weren't present from the previous games, such as regular base invasions, micromanagement and unit counts. Thankfully there have been mods to help supplement what some of us old-school fans were craving from the newest XCOM. It at least looks like Firaxis has also taken into account that some of those cravings from the old-school fans just might make the game more interesting, hence the whole personnel betrayal subplot.
They've also added in new unit management types, including the ability to take your soldiers and turn them into cyborgs, which is a neat little twist that I completely did not see coming along with the new mech units. You can modify a soldier's arms, legs and chest, pretty much making your own Robocop or Exoman. How well these cyborg units will affect gameplay remains to be seen, but I definitely like the addition of something to change up the formula on the battlefield.
Speaking of battlefield formula... unfortunately the game still limits soldiers to six units on a mission at a time. This is by far the most frustrating thing about the newest XCOM, especially for people who enjoy playing the game a certain way or using certain tactics.
Thankfully Nexus has come in to save the day and modders have a number of different modifications for the PC version of the game (sorry console gamers, you're fresh out of luck on this one). The Warspace Extension adds a bit of depth and difficulty to the game while the Long War mod adds additional unit counts to the battlefield, so you have a few extra soldiers at your disposal as opposed to the standard limitation of six units per mission.
There's really no telling how compatible the aforementioned mods will be with the newest Enemy Within, but they are worth checking out as potential options to really help expand and enhance your play experience with the game.
I'm just glad base invasion will be a regular theme to Enemy Within, because the thrill of having your base attacked was always one of the highlights of the first three games. You can learn more about the mods over on the Nexus website.