If you want a good game for strategy in a fun first person shooter try Arma 2 Combined Operations. If you buy it get the Arma 2 Combined Operations of the original and expansion bundled, under $30 for the game and expansion.
Here is a tutorial for taking a long range shot on the game:
http://www.youtube.com/watch?v=u2hI9Dvorz8
It has a decent learning curve but is far better than the more popular well known games.
It is a sandbox style game there is no stages or loading between areas, the entire world is open at a time. For example one area is 225km squared in size, all in use at the same time. It has various vehicles that add to the strategy from aircraft to armor and light vehicles. Vehicles are not done as simulators, but that also means your average gamer can transport a team in a chopper, not just someone that plays flight simulators.
There is a built in editor and it is highly customizable, and various mods that adjust the game can add to realism, as can some settings.
Servers or groups that play together can dumb it down or make it more realistic.
It is really well done, and includes elements most won't even notice like vehicles with the engine off cooling down and becoming less visible through thermal optics.
Some servers turn off crosshairs, third person, and hud.
Variables can be adjusted making death everything from permanent, to even a wound disabling and disorienting someone and requiring treatment, to more common and popular but unrealistic medics able to revive. One mod requires medivac and treatment back at base to ever 'respawn', though such things are less likely to be popular because players won't wait that long to start playing again.
There is many mods to adjust the realism in different areas.
Here is an example of some manual use of mortars, from a mod that adds that feature:
http://www.youtube.com/watch?v=uJCD8kOK3WM
Many similar things are created by community made mods, which the game is designed to readily incorporate. This allows people to make it as realistic as they wish, and some servers and groups require certain mods.
http://wiki.ace-mod.net/ is pretty standard as one of the mods everyone uses as a start.
In addition to many other things this mod adds wind, better elevation, and adjustments for windage.
Certain groups of people play together or belong to clans or 'squads' that they mostly play with, allowing them to control the maturity level and limit who they play with.
Pace can be slow but some people play it well as a team, this server has third person and hud etc enabled:
http://www.youtube.com/watch?v=krLtYiChXS8
Every element of the basic game can be modified and adjusted with various mods. If someone has a problem with something, a mod exists or can be made to address the problem.
Missions can also be designed from the ground up in the editor.
The only complaint is that the AI can be bad sometimes.
Arma 3 coming out towards the end of the year looks like it will be even better.
As for the OP, games are entertainment. There is no muzzle blast that really hits you, recoil, required full body coordination, developed muscle memory, or varied equipment malfunctions and similar things one must attempt to resolve.
In a game you can talk during and after firing a .50 caliber machinegun in a normal voice and understand what is being said.
Aiming with a mouse or controller has little in common with aiming and operating a firearm. The steadiness of your hand, breathing, etc are very different. You don't actually support a firearm, or have tons of gear on.
Shooting in games as a result is either too easy, or build in some element to make them harder to compensate that is generally unrealistic and you may actually shoot better in real life most of the time.
Most games don't even aim for even a percentage of realism, and instead adjust firearm mechanics for arcade balance.
For example an m249 may lay down a lot of fire, but do less 'damage' than an M4 which takes more aiming to score hits with. All to add balance, when in reality they are both using the same round and the m249 has a longer barrel giving higher velocity and so is actually more lethal per round.
There is also no fear or lasting consequences. People don't die, get maimed for life, and most games don't even punish people with a respawn more than a few seconds long because the average player won't approve.
This creates very unrealistic willingness of everyone to jump into harm's way and be less cautious or strategic.
All elements are know and expected confined to only the limits of the game mechanics, real life is full of the unexpected and those who adapt to it better can succeed even when those better at doing the expected do not.
Games also don't teach proper firearm discipline. Your typical FPS for example has your view locked to your weapon. Muzzling sweeping and even aiming at everyone is normal. The opposite of what you teach someone to do.
Most games also require no target identification, the enemy is easily identified, and one can engage as quickly as physically possible. Most also lack downtime so someone can stay in high alert for the next engagement a few seconds away. The individual is not thinking and working on something else before the unexpected happens after hours or days without a problem.
This creates a situation where the person that thinks less and reacts fast prevails in a game.
In real life that is often not the case, most time even in a war zone is spent doing something mundane and the high intense moments are far apart and often unanticipated, but brief and deadly.
Games also place you on an equal footing or an at advantage. They are designed so a regular consumer can clear out a level or area with dozens or hundreds of enemies directly engaging them in close quarters, and survive if they play right. Then repeat it again. Nobody is actually that good or lucky. In real life some of the best, the most skilled, or the bravest, die. While some with half the skill survive. There is a lot of randomness.
Finally acting like games equate to the real thing belittles those who actually are risking and sacrificing. Even an interactive simulator as realistic as possible for say a military based experience does not require sacrifice.
They don't require one to really put themselves in a situation where even if they do everything right they and others they are with may die, suffer lifelong injuries, or have their actions second guessed by people safe and comfortably sitting down thousands of miles away.
You don't die or suffer injuries due to following certain rules of engagement, or get court-martialed for disobeying them. You don't have to make decisions and act after days of limited rest, long periods of extreme stress from risk of death if you miss a sign of an IED, ambush, or other risk while performing what is normally dull boring menial tasks.
They are also cleaned up, and real horrors and morality questions common in war for example are not raised.
Games remove huge numbers of elements that add to the mindset of people in situations, and make it a fun experience of constant action and skill. Rather than what it really is.
When a child plays a game based on a historic event and thinks they know what it was like, a brief action paced game of skill, it does a disservice to the experience, while at the same time highlighting just some of the innocence that child has not lost through what the actual experience would have involved.
While in civilian firearm use there is also moral and legal issues, and use of a gun is not detached from these things like a game allows one to become used to it being.
Life is not a game, you get one try.
), and the developer, Dice, did an incredible job rendering accurate gun noises, recoil, bullet drop, ambient sound (you can actually hear the bullet whiz past your head on a near miss), and destructible environments (buildings can be brought down on your head at times). It offers the average person a safe way to get some real excitement. There are plenty of times I have been pinned down lying prone behind a piece of concrete, watching as it chips away with enemy bullets rattling into it. It's a very "real" feeling if you let yourself get caught up in the game. 
