In brief:
- If you're an Arma enthusiast, Arma 3 is a _must_!
- If you don't know the Arma series, this game is a MUST :) !

Infantry simulator, with the ability to drive vehicles (Land, Air, Sea) with high degree of fidelity and real simulation.
Physics, gameplay, story (for single players), graphics.
The game is just awesome.

Warning: if you're picky (might commit suicide on the first pseudo-bug encountered) or you like FPS action, John-Wayne-style, this IS NOT for you.
This is more a simulator than a shoot-em-up game, where tactics, speed of wit and experience play an invaluable role in the missions.
And sometimes, things don't behave as expected... But rarely... But it happens...

However, if you like to zero up/down your sniper scope to compensate for the distance, if it makes you happy to carry a couple of weapons in your backpack, your magazines in your bandolier and night vision goggles on your combat helmet, if it matters for you to enter a vehicle and find most of the internals working (like speed/fuel/RPM gauges, mirrors, screens...), if you like UAV's and small drones that fit in your backpack, if you like to select your ammo type (tracer, belt, regular mag), if you find it awesome to play in an environment with kilometers of view-distance, if it engages you to play a game where there is no health bar, but every bullet counts (both the ones you deliver or receive), if you like to customize the game and create your own scenarios and campaigns and play them with your friends, if you like to play Zeus (yup, the Greek God, with the Lightning bolt)... If... If...
If all (or most) of the above apply to you, well, this game is for you.

This is one of the games I can't recommend enough.