Successfully complete the game after finding all fifteen 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 ammunition (500 bullets, 50 shotgun shells, 30 grenade rounds, 1,000 flame units, and 25 Ultimate Launcher missiles) and extra health items (20 Recovery Unit A, 5 Recovery Unit B, 5 MTS Vaccine, 5 Booster Shot A and 3 Booster Shot B). However, enemies will be more difficult in this mode.
Complete the game with Roger's Knife collected. Save the game when prompted to create a file name in yellow. Load the file in yellow to start a new game with extra ammo.
Extra Healing Items
Complete the game with all Dog Tags collected. Save the game when prompted to create a file name in yellow. Load the file in yellow to start a new game with extra healing items.
Dog tag locations
The following are the locations of the dog tags in order of when you find them:
#5 Corporal Ross Dixon. Once the dust clears from the train wreck in the train area, go through the hole the train made. On the platform to the right, between two metal boxes, is the dog tag.
#4 Corporal Arthur McDonnel. In the Command Center (where you use the 51204791 code in the computer) reach the side where the computer is located. If in the box, the dog tag is to the left of the computer, outside. Go to the outside corner of the box, where you can look over the electric stream. The dog tag is next to the box. You should see it shining.
#1 Private First Class Hans Grant. After defeating the Boss from the freight elevator, the dog tag is left behind, on the treadmill.
#12 Lieutenant Mat Shuggart. After grabbing the parka, go up the ladder next to where you came out. Up there you should see the dog tag before the bridge across to the corpse and the detonator.
#11 Second Lieutenant Chris Ditter. After coming in the Filtration Plant through the tool shed (you came in a by a ladder), make your way to the left. There should be a slope with a little bit of ledge. Climb across that ledge and make it to the platform across. Get up on the little bit higher platform. Under the platform, is the dog tag.
#9 Officer Cadet Ed Collate. After getting the dog tag receiver unit, duck under the platform next to the staircase. Slice the trip wire, then collect the goodies: A SPR4 magazine, shotgun shells, a flame thrower tank, and dog tag #9.
#6 Sergeant Robert Cameron. Near the wrecked train, where you first meet the watchdogs, use the dog tag receiver unit to find it.
#7 Sergeant David Murren. Once coming through the door of the train room, you should see a booth or something straight ahead. Slice the wooden crates to the left of it and you should see it to the right of the steel crates.
#13 Captain Kurt Gianini. Up the stairs, in the same room, there should be a vent in the area where you look down on the booth area. Once in, take the first right and go straight until you reach the end. Turn right and there they should be at the end.
#3 Private First Class Tom Taylor. In the room with the metal tag, same area as the other two above. You should find it by the metal tag.
#10 Officer Cadet Lance McLaughlin. After confronting Cindy, you should find this tag in the corner near her.
#2 Corporal Filel Sidalis. On the ledge outside, near Filel, there is the dog tag on the ledge. Use the dog tag receiver unit.
#14 Sergeant Roger Grigman. After defeating Roger, the dog tag should be just before the bridge. Also take his knife.
#15 Major Mike Madigan. After defeating Roger, go to where the wounded Madigan is located. Once the FMV sequence is over, his dog tags will be next to the elevator-like thing where he descended into the Facility.
#8 First Sergeant Ken Reschner. In the area with the ice camo car, the dog tag is in the corner of a little outcropping. You should now have 14 out of 15 dog tags.
Defeating the four final Bosses:
Part 1: Roger has left the facility and gotten on top of the of the plant. To defeat him, you need to kill him, once and for all. Go left from the beginning and climb the boxes. Go all the way to the side and get the Booster Shot-Type B. Then, jump through the opening, and get onto the roof. Shoot him with a grenade, then run. When he raises his knife he will charge -- run around and shoot him again. After awhile, he will die. Pick up his knife then go to the major.
Part 2: After launching from the facility, you will notice that the hovercraft shakes. Go outside and search the ship, finally entering the save terminal area. This FMV sequence shows the "Origin". Your first priority is to get on top the armored vehicle. On top are gun turrets, which you need to get in. Press the action button (default X) to get inside. Now, take some shots at the flying Origin coming by you. If you see little blob-like figures coming straight at you, jump out of the cockpit and wait for them to hit. After that get back in and keep shooting. You can only shoot the Origin once in its leap.
Part 3: After you think you kill the Origin, it comes out and destroys the armored vehicle. You have no choice but to take the left ladder. Once up, go up the catwalk and take the pulley down. Push the directional button to go down the harness. Once down there, you need to get in the machine guns. After 15 seconds of continuous shooting, the guns will need to cool down for 30 seconds. Watch the red bar in the corner and as it creeps up, let off the guns. Shoot the core in his chest at all costs. Otherwise, do as much damage as possible.
Part 4: After it dies, an evil Dennis spawns. Take out your SPML (rocket launcher) and shoot at him. After 5 or 6 shots to him, he will finally go out cold, ridding you of the H0213 forever. Watch the credits to the end, then save.