Surprisingly, this additional final level of the NES version does not feature a tremendous amount of variety. You will start out on the bottom level, but will soon have the option of climbing up to the top level. The top level only affords you a modest amount of extra safety since you will never have to deal with land mines up there. Also, there are gaps in the upper floor which cause a lot of the soldiers chasing behind you to fall to the floor below. You will face the usual combination of foot soldiers and combat specialists, with a yellow gun soldier thrown in every now and then. If the soldiers advancing upon are you spaced far enough apart, you can leap over the foot soldiers, and allow the foot soldiers to leap over you, but this should only be done if another soldier isn't close by.
After a very long stretch of the above, the only unique aspect of this stage shows up right before the ending. Eventually you will be forced to drop down to the lower level. As you run along the floor, and continue to get attacked by soldiers, you will notice yellow gun turrets mounted on the ceiling. These turrets fire blue lasers at you. As long as you keep running forward, you have very little to worry about, even if you have to stop to stab the occasional foot soldier. When you reach the black area beyond, very carefully take out any soldiers that were following behind you before you scroll the entire final scene into view.
In this version of the game, your final objective is to destroy the enemy's secret weapon, and here it is right in front of you. You must destroy this giant missile, and your machete won't even scratch it. When you arrive, the alarms will sound, signaling a bunch of soldiers to attack you. Mixed in among each group of soldiers will be two supply runners. They will always carry rocket launchers. Do your best to destroy every soldier and collect the rocket launchers that the supply runner drop. You must hit the giant missile with 12 rockets to completely destroy it. Once you do, the game will be over and you will be treated to the ending.
There are a couple of differences between the US and Japanese version. The US version is much easier because no enemies will ever attack you from behind. This means you can stand still in one place, stab constantly, and destroy every soldier including the combat specialists. If you stand just in front of the missile, the rocket launchers will bounce against the right wall and back to you, so you won't even have to move. The Japanese version is more difficult since you do have to worry about enemies attacking from behind. You also only get one shot per supply runner that you attack, so you'll have to go through a few more rounds to get all 12 shots in. In the Japanese version, you should stand slightly close to the missile, holding your position and stabbing constantly. Only turn around and jump up when a combat specialist is close enough to jump kick you.