video game, Halo MCC, playing on Steam Deck, first-person shooter, sci-fi armor, Master Chief, dynamic action pose, futuristic weapon, energy sword, alien landscape, Covenant enemies, UNSC vehicles, Warthog, multiplayer map, space station, vibrant HUD, interactive controls, handheld gaming, portable device, ergonomic grip, SteamOS interface, high-resolution display, ambient lighting, indoor setting, focused gamer expression, casual attire, 3/4 view, atmospheric backlighting, detailed textures, immersive experience, real-time rendering, action-packed scene, science fiction environment.