- New separate storylines pertaining to the backstories of Jonathan, Chandra, and Jack before the events of Perfect Dark Zero.
- There could have been MedKits in the game, which restore maximum health up to 100%, just like in Doom 3. On Dark Agent, though, those MedKits should disappear altogether.
- Giving enemies stronger weapons on higher difficulties.
Examples would include:
- Enforcers carrying SuperDragons on Perfect Agent/Dark Agent in Nightclub Stakeout
- Biker punks carrying KSI-74s on Secret Agent in Subway Retrieval
- An 800-round ammo cap for the pistols, SMGs, rifles, etc. The DEF-12 Shotgun would get a maximum of 320 shells, the DY357 Magnum 288 bullets, Rocket Launcher 50 rockets, and Jackal 100 rounds.