In order to achieve Big Boss rank, you need to meet the following requirements:

-Difficulty: Original
-Play Time: Under 1 hour 45 minutes - Game Timer can be paused by going into Data Save/Load menu
-Number of Saves: No Limit
-Number of Continues: 0
-Number of Alerts: max 6 (2 Unavoidable)
-Number of Enemies killed: max 5 (Try to keep 5 kills for the very last sceen of the game)
-Number of Rations used: 0
-Special Items: Not Used

Building 1

Outside
- Ration B1 (truck) - Pistol (2nd truck)
2F
- Card1
3F
- Card2
Jungle
- Call 140.82 inside the jailhouse - 7 Mines(minimum) - Card 3
1F
- Stinger

Building 2

Outside
- Box (truck) - Accept Campbell's call
1F
- Ration B2 (in second screen duct) - Accept Holly's Codec call - Take 2nd elevator down (counter clock-wise)
B1
- Plastic Explosives - Card4

Building 1 (Through sewers)

B1
- Grenades -

Building 2 (Through sewers)

1F
- Take the center elevator

4F
- Pigeon (Ration B2 needed to lure) - Call 140.51 - Call 140.82

1F
- Take 1st elevator down (clock-wise)

Building 1 (Through sewers)

B2
- Travel to 2F, change elevators and to 4F

4F (Save recommended to avoid RNG alarm in mannequin room)
- Call Madnar just in case in case - Bucket

After the Bridge Scene
- Mines left-most truck

Building 1

1F
- Hand glider

4F Freezer
- Freeze the Brooch - Ration B2 - Ration B3 - Use Gustava's elevator to get back

Building 2

Bridge area
- Loot all the mines in front of the 4 trucks and the truckes themselves

1F
- Take the first elevator you encounter Counter-clock wise - After Boss fight, First elevator Clock-wise

10F
- Save recommended to avoid damage

Building 3

Western Path
- Card8 - Egg (Left side) - Avoid the Egg on right side

Path East
- Loot the Truck on the right

Detention Camp (Need 3x Ration B1)
- Ration B1

Detention Camp
- Neutralize Acid spills with Rations B1

Western Path
- Return for Card9

Madnar's Cell (Enter Mice room, leave and lure mice out with Ration B3)
- MSX Cartridge

Big Boss Arena
- Ration B1

Order rooms and items in them:
6 3 7 2
8 1 5 4

Last Screen of the game
- Here you might have to Kill all the guards on the screen, but wait about 20 seconds before doing that so they don't respawn immediately - When all are dead, fire your pistol to end the game.