Your style is very impressive, and the accoutrement detail is fairly accurate. However, while it may be unofficial in nature, some aspects of the art must be observed and (potentially) rectified. I fell that, as the art composition is meant to be based upon Marcus Fenix, the face should be far more aggressive and weathered. I would recommend observing several images of Fenix; this would aid in magnifying the likeness between your artwork and the in-game character. Also, considering the game that Marcus originates from, the armor and weaponry would not be as clean-cut as depicted. I would suggest adding multiple scratches at the least, or deep gouges and the additional gore at the most.