A good game for some realistic military gameplay.
and not that Call of Duty or Battefield Nonesense.

Mil-Sim groups are great as long they do it right....i have had my share of bad ones to experience :|
(Luckly i found a good one for my self now)
They make the game even more Realistic with the help of great mods available to all made by some amazing modders such as ACE / RHS / JSRS Soundmod to name a few.

Fun-fact: Some countries have a other version of Arma 3 that is only available to the army to train soldiers virtually.

1 minor point is that Arma 3 sometimes like to get you a typical Arma moment.
(Where suddenly strange things happen or glitch out but these are only rarely and when they happen i most often find them hillarious for what happens than but is sometimes as well annoying)