Bohemia Interactive's free-to-play shooter Argo emerged first as a total conversion mod for Arma 3, but now it's available as a standalone title.
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The free-to-play title finds mercenaries working against each other on the island of Malden, where the first Arma game took place. This shooter is meant to be a much more frenetic and twitch-based affair, with unlockables, leaderboards, co-op play, and even a scaled-down version of the 3D Scenario Editor from Arma 3.
You can download Argo for free via Steam or the Bohemia Store. There won't be any microtransactions or premium currency. If you want you can purchase the Argo Supporter's Pack for additional MVP animations, clothing items, and other goodies, but that's about it.