It is possible that the Advanced Soldier RIG first superseded the Legionary Suit and is a Marine's variant of the Soldier Suit.The helmet resembled a human skull minus a lower jaw, complete with a hole corresponding to the nasal area.The Soldier Suit and EarthGov Security Suit that are featured in Dead Space 2 are also military-issue combat wear, but differed markedly in appearance.Additionally, Isaac seems to wear a balaclava and gridded lower mouth guard.
This is applicable to both the original Dead Space, and the remake. Once loaded, head towards a Store (Which is first seen near the tram at the end of Chapter 1). The Soldier RIG costs 99,000 Credits and is available for purchase after loading a "Cleared Game" save.