SPV3's campaign follows largely the same story as Halo: Combat Evolved and Halo: The Flood, but with additional characters and events. It was designed so that it could effectively take the place of those two pieces of Halo media, without causing any discrepancies or inconsistencies in the process.
The gameplay in the mod is largely similar to that featured Halo: CE, albeit with a larger sandbox of weapons, vehicles and enemies. In addition, features such as boarding, vehicle EMP, loadouts and armor abilities from later Halo titles have been introduced. The developers aimed to preserve the design philosophy of Halo: CE, allowing for enemy encounters where the player is allowed to choose how to approach the situation rather than being forced through a linear path.