A super-realistic modern shooter, "ARMA 2" has a bit of a learning curve, but can provide satisfying, in-depth tactical experiences.
"ARMA 2" is a first-person shooter developed by Bohemia Interactive. It was developed with many aspects similar to an actual military training program used by armies worldwide. Most notably, ARMA 2 is incredibly realistic with regards to things like ballistics, weapon range, and weapon damage. The usual FPS run-and-gun tactics won't cut it here - teamwork and quick thinking are a must to be successful in ARMA 2. Some relatively simple changes to the usual FPS framework make realistic tactics a necessity. For example, being shot at makes your aim less accurate - as such, the tactic of "suppressing fire" works in ARMA 2 when it does not work in most games. These tactics aren't too hard to learn, but gamers trained in traditional shooters will have to shift their thinking about how to win.
ARMA 2 has an extensive single-player mode, featuring campaigns as well as individual scenarios, but the game's best aspects are found in multiplayer (whether cooperative or competitive). Players running around willy-nilly make easy prey for coordinated players who make good use of communication and tactics. The maps are huge to allow for vehicles, which also means that soldiers can engage at realistic ranges (from hundreds of meters away). This prevents the standard spray-and-pray mentality from gaining ground.
The game features a robust editor for creating single-player or multiplayer scenarios. Some light scripting is required, but there are plenty of easy references on the internet for it. For the most part, the editor is intuitive and simple - place units, place waypoints, place triggers, and so on and so forth. The game is also fairly easily modded. A variety of expansions and DLC packs provide even more content - "Operation Arrowhead" is the biggest one and provides the most benefits, while the other ones are recommended only for people who are really interested in their niche subjects (like "the Czech army").
The game's graphics aren't exactly great, but considering the scale of the game this isn't really surprising. They're certainly "serviceable" - not ugly, but just not up to the par of modern AAA games. The game's sound is a little weak, too, but unlike many games the sound serves a gameplay purpose. There is no "useless" background noise - every gunshot has an actual source on the map, and every spoken word communicates actual information about what allies (or enemies) are doing. Especially notable is the game's disjointed voice system, where characters will give orders and refer to objects or people in an "assembled" manner. For example, an AI commander may give an order to "move" "right" "50 meters", with each fragment being spoken separately. The overall effect sounds weird, but is useful for conveying information "naturally" rather than in a scripted manner.
Overall, ARMA 2 is certainly a different experience than most games, and may frustrate gamers looking for a quick pick-up shooter, but the depth of play involved offers an incredibly distinct experience that shooter fans shouldn't easily dismiss.