I've been seeing a video option hovering on my YouTube feed for the past few days for something called Operation: Trebuchet. It wasn't until tonight, while perusing Kotaku, that I came upon the unofficial gem that this game might just become.
A mod of Arma III, Operation: Trebuchet takes the realism of the former series and adapts it to the legendary Halo series. Yes, you heard that right. It's basically two games in one. The game is currently in Alpha, and you can check it out on in the Steam Workshop. The setting is inspired by the last human-vs-human war before contact with the Covenant was made. The idea, as stated by its developers, is to put players in the role of a "grunt" combatant, as opposed to the super-soldier Spartan units. Although in the trailer, which you can view below, packs a few nice shots of not only the Spartans, but Elites and ODSTs.
It will be interesting to see how it all plays out, I hope for the best.