Halo 3: ODST

Step out of the role of a Spartan and into the boots of an ODST (Orbital Drop Shock Trooper), another branch of highly trained UNSC (United Nations Space Command) soldiers. This game offers a much different Halo experience mostly because of the absence of the Spartans' lovely MJOLNIR shields, along with the added ability to roam freely around the playable area, amongst many other traits. This game also introduced the Firefight mode, where you battle waves and waves of enemies.