Unlock Secret Mode:
Successfully complete the game after finding all 15 dog tags and Roger's Knife.
When the credits have rolled, save your game and you'll notice that the svae file is yellow with a star next to it.
When you load up this file, you'll start a new game with 300 bullets, 50 shotgun shelss,
99 grenade shells, 1000 flame units and 25 missiles plus an AT-6 Grenade Launcher.
Youalso get 25 Recovery Unit A, five Recovery Unit B, five MTS Vaccine,
five Booster Shit A and three Booster Shot B. Be warned that enemies are much
harder to kill in this mode!
Unlock Expert Mode:
Successfully complete the game after finding all 15 dog tags and save. Start
another game with the yellow 'Rear of Compound' save file (00:00:00 time).
The game will begin with extra ammo (500 bullets, 50 shotgun shells,
30 grenade rounds, 1000 flames units and 25 Ultimate Launcher missiles) plus
extra health items (20 Recovery Unit A, five
Recovery Unit B, five MTS Vaccine, five Booster Shot A and three Booster
Shot B). Be warned that enemies are harder to kill in this mode.