The team has been working on the mod for a couple of years now, and while it's still in alpha, you can download it now and take it for a spin. Well, a regular person who still has access to futuristic weaponry and fancy, heavily-armed vehicles. Like Arma 3, it looks a lot more grounded than a typical Halo romp, but judging by the impressive new trailer, there's still plenty of sizzle. Set during the titular conflict between the UNSC and insurrectionists, before the arrival of the Covenant, it focuses on regular soldiers and rebels rather than the superhuman Spartans and aliens we're used to. Operation: Trebuchet, a Halo mod for Arma 3is taking the Halo universe back in time.