Learning Hotkeys is a vital skill, mastery of these few commands will save you having to constantly move the mouse to click an icon or trigger a power on your selected squad.
Your squad mates have certain standard abilities that are tied to the wargear they posses, as well as their equipment. They can throw frag grenades in the case of Tarkus, or Cyrus can slip into Infiltrate mode and sneak around the map for a while. He can also hurl det-packs at enemy buildings and blow them to bits. Avitas and his Devastator squad are capable of laying down an insane amount of suppression fire and Thaddeus is equipped with a jump pack and can rain death from the skies on his foes.
The game is far more tactical and you're able to make use of cover and special abilities to approach each situation, adapt your tactics and change your approach very quickly. Units in cover, behind walls, to the side of buildings and so on are less vulnerable to damage from enemy fire.
Since Relic has concentrated on small squad sizes, usually three men in a squad, you can get a feel for these soldiers under your command far more in terms of their abilities. Tarkus is excellent at ranged firepower and breaking enemy formations with grenades. Avitas can lay down a suppression fire with his Heavy Bolter squad and prevent enemies from advancing or even escaping in some cases. Cyrus can utilise close quarters weapons or even sniper rifles to make quick work of distant threats.
There are several structures that you can capture in the missions, they unlock specific Wargear and provide an overall campaign bonus when you have enough of them in the system. Once they're captured the Battle Barge will send down generators to secure the building and in defend missions you must keep these generators from being destroyed. You may only capture one building per deployment to the planet.
Once you've finished one of these missions you'll be taken back to the Battle Barge: Strike Cruiser - Armageddon, high above the planet's orbit and given a debriefing. You might have earned Wargear and valuable experience. It's here that you can assign your 4 squads, level up your Commanders and swap out Wargear, selling any you don't use or can't be bothered with for extra bonus experience.
Each Commander has a number of stats that they can level, by 2 points per level up. Health, Will, Ranged Power, Melee Power and so on. Along the way on these tracks are traits that will unlock when you reach a certain point. These traits range from an extra accessory slot for certain Wargear to special abilities like Cyrus' squad being able to move at full speed whilst infiltrated. It's not possible to get every advance so you're going to have to decide on the roles for your squad leaders and focus on those with your hard won experience.
Wargear will change certain statistics, rather like in an rpg you can equip your leaders with new weapons, new armour and things like the Signum, a device that allows you to call in artillery from nearby stationed Imperial Guard batteries. Again, along with squad selection, the meta-map and equipment/statistic exchange/boosts this elevates the single player campaign into something far more interesting. It becomes a tactical game even in the assignment of these factors.
Whilst there is only one campaign, the Blood Raven's campaign, you can play this whole campaign with a friend over Games for Windows Live, just like inviting a buddy in on the Xbox 360 Xbox Live service. You'll also earn Achievements for the game for those people who delight in increasing their gamerscore. It links up with your Xbox Live profile if you have one, so it adds to that.