It's an free standalone ARMA 3 conversion that tries to be fast paced (like Counter Strike?). But what is it really? Anyone tried?
http://store.steampowered.com/app/530700/Argo/#app_reviews_hash
From what I have seen its a small unit (5vs5) tactical PvP shooter, with Arma 3 assets.
Aparently there is also a PvE game mode where you can play with up to 10 people against randomly generated enemy opposition.
(https://s-media-cache-ak0.pinimg.com/236x/8d/f1/4a/8df14a58b298f718a16228a08696f047.jpg)