doomslayer, male, helmet off, intense gaze, scarred face, stubble, short brown hair, battle-worn expression, space marine armor, green, metallic texture, heavy gauntlets, first-person perspective, close-up, Mars landscape, hellish environment, fire, brimstone, dim lighting, high contrast, dynamic angle, action pose, holding shotgun, detailed texture, gritty atmosphere, advanced HUD display, cybernetic enhancements, ultra-realistic.