In this mode, the Mutants received an attack boss with a host mutant called Xeno, who can see soldiers' position, has longer attack range and a bulletproof shield that can reduce damage taken to minimal, allowing him to rush soldiers with ease. To make up for this, Soldiers have a whooping 240% attack power boost at the start, and this number goes up 10% every time a soldier is infected.
Each round lasts 2:30 just like in Hero Mode, and when there's 60 seconds left, all surviving Soldiers have the option to transform into Super Hero/Ranger to enter an all-out Duel against the Mutants.
- Despite sharing the same name with its PC counterpart mode, Hero Mode X features different gameplay mechanic than HMX in the PC version. The original HMX is instead called Mutation Terminator.