Forbidden Siren Cheats

Brain Cell Revival (Zuno) puzzle mini-game:
By finding Archive 087 in Kyoya Sudo's stage (03:00 on Day 3).

Time attack mode:
After finishing the first two objectives on all levels in every scenario you will unlock the first ending sequence. Then, press Square at the scenario selection screen.
User Cheat by Royal_Steve

Hidden FMV sequence:
After finishing the game and finding all 100 Archives. A bonus FMV sequence will be unlocked at the top right corner of the scenario selection screen.

Mission Objectives 2:
If you want to unlock Mission Objectives 2 for every character and/or scenario, finish 19 stages in any order. Then, press L1 + R1 while the stage is highlighted at the scenario selection screen. REMEMBER: You will automatically obtain it after completing the random 19 stages.