I'm a huge fan of Gears of War. To me, this is the Shooter to end all others. Ever since the days of Halo and the "Halo Craze" that enfused the Xbox with life, every FPS, Tactical shooter, etc.... and it's Grandmother have been dubbed the "The Halo Killer." To them, I say, "Pah."
Gears of war is a Strategic Third Person Shooter, otherwise known as "STPS." It's main premise is that of using cover effectively, utilizing teamwork, and above all, remaining tactically fluid.
To begin with, I shall expound on the wonders of the glorious A button:
You can "slam into" cover merely be being close enough to it, centering your view on it (or merely be looking "at" it, if you don't or can't take the time to center), and tapping the A button.
You can initiate a roadie run by holding down the A button. If no input is given with the left joystick you will simply run forward. If you are holding in a direction (such as backwards, in order to run away from the bad man with explosives), you will initiate a quickturn and roadie run in that direction. What "roadie running" does, is put you into a "sprint," granted that you are wearing far more than 50 kilos of armor/weapons/etc, you'd be surprised how fast a soldier can haul ass when needed. You can't manuever quite as well while roadie running, nor can you attack in any manner. You can, however, reload.
Tapping the A button + a direction on the left joystick will put you into a roll. Rolling is bad in close quarters. Because a roll takes a set amount of time and you cannot change the direction of your roll or end it prematurely once you begin. Therefore Mr. IHaveMyShotgunsBeadOnYourFace will..... usually not be deterred by such a tactic.
The next thing I'm going to point out is the "active reload" feature. This is an amazing premise. What it does, is, in the normal second or so it takes you to reload, offer you a chance to try to get an enhanced reload known as an "active" reload by tapping the reload button again at the appropriate time. A grayish bar appears below your weapon icon (where your ammo counter would normally be), while reloading. Depending on the weapon, a white line appears at a fixed point on this bar. As you reload, another white line appears at the left end of the bar and travels to the right. If you nail the "active reload" when it is precisely aligned with the "static" white bar, the bullets you have just loaded will shine light and dark in your ammo display. These bullets do more damage, and have a bigger radius of "explody death" (sadly, this is only with explosives as even an active reload does not grant a standard bullet explosive properties). If you just barely miss the static white line, you simply reload your weapon faster than normal, which is still a very nice thing. However, if you fail by more than a small amount, congragulation! You have jammed your gun. Please feel free to wet yourself and run like hell as your foe does all in his power to turn you into a deflated sack of meat. Another very neat feature of the reload system is the fact that there is a chance that your results will, effectively, be "broadcasted" to everyone. Each character model has specific lines that they will sometimes say upon achieving an active reload, such as "It's a hat trick," or "Hell yeah!" or (in the case of the particularly evil looking Locust Grunt), an evil chuckle. If you jam your weapon, it is equally likely that you will swear or emit some other phrase or sound associated with your displeasure. Such sounds can be heard by everyone still living, friend or foe alike.