Life Force/Gameplay

Controls

 * : Use the direction pad to pilot the Vic Viper or the Lord British in any one of eight directions. Although the screen scrolls automatically (forward on the odd stages, upward on the even stages), you can travel to any visible portion of the screen.  However, you cannot collide with any part of the terrain, so you must steer clear of any obstacles that occupy your path.
 * : Press the power-up button when you would like to activate whichever selection is highlighted in the power-up bar at the bottom of the screen. You can only use the Power-Up button when a selection is highlighted, and the words are present in the selection.
 * : Press the B button to shoot your weapons. Your primary weapon is either regular shots, ripple lasers, or laser beams.  If you have collected the Missile power-up, pressing B will launch missiles on either side of you.  Holding the button down allows you to fire continuously, although it's possible to fire more rapidly than holding the button down ordinarily allows.  Holding the button down with laser beams allows you to fire the longest possible uninterrupted beam.
 * : Press the start button to begin a new game, or to pause the action mid-game.

The ships
Player 1 is the pilot of the blue Vic Viper, while player 2 is the pilot of the red Lord British. The Vic Viper has been slightly upgraded from it's previous battle in Gradius. The Double weapon has been replaced by the expanding Ripple Laser, and the original Laser has been upgraded to what is known as the Cyclone Laser. The Lord British was developed using the Vic Viper as the basis for its designs, and is fully compatible with all of the same weapons modules.

You must fly the Vic Viper and the Lord British through six stages in an effort to defeat their leader and save your home. Both ships are extremely maneuverable and powerful, but they do not start out this way. As certain enemies are defeated, they will leave power-up capsules which can be collected by the ships and utilized to activate additional weapons and functions. When either ship is launched, it starts the mission out at the slowest speed with only the most basic weaponry. You must collect the capsules in order to build up the destructive power of the Vic Viper and steadily increase your offensive abilities.

Power-Ups
Throughout the game, the Power-Up bar can be seen at the bottom of the screen. As shown above, they appear differently depending on the region of the game. In the Japanese release, the meter looks more traditional, showing all six names in a full sized meter. In North America, two shrunken bars are shown side by side, indicating the currently lit bar, as well as the name of the bar which is lit. Both bars identify six selections that you may choose to power the Vic Viper or Lord British with. In order to choose a power-up, you must collect the power-up capsules that enemies leave behind. For each item that you pick up, a selection will be highlighted, starting with "Speed", and continuing to the right one space at a time. If you collect another power-up capsule when "Force" is highlighted, the selection will wrap around to the left and highlight "Speed " again. Whenever a selection that you would like to choose is highlighted, you press to activate it. All of the power-ups are described in detail below.

This is the power-up capsules which is left behind by different types of enemies. Most enemies have a standard color, usually some variant of gray. However, when an enemy is predominantly gold in color, that is an indication that the enemy will leave a capsule behind when destroyed. Power-up capsules are also left behind by formation enemies; enemies that come out in large groups or chains. If every enemy in the formation is be defeated, the last enemy defeated will leave a power-up capsule behind.

Certain enemies will deposit a blue crash capsule instead of a red power-up capsule. Running into the crash capsule will destroy every basic enemy present on the screen at that time. It will not affect your power-up bar in anyway. Although you can't rely on them for your strategy, they can save you during very difficult moments.

If you happen to fire your weapons around difficult locations and very tight corners, you may reveal a 1up capsule. Collecting one of these will increase your remaining ship supply by one. These capsules are always found in the same locations from one game to the next, so memorize their positions once you discover one.

Speed
Speed Up naturally increases the speed at which you may maneuver your ship across the screen. The more Speed Ups you apply to a craft, the faster it can fly around obstacles and enemies, or line up with oncoming enemy crafts. The Speed Up power-up can be selected five times before it maxes out. However, you should not collect this power-up to that extent. Doing so will cause a condition known as "over control," which occurs when the ship moves too quickly for you to make meaningful adjustments to its position in space. Every player has a speed at which they are most comfortable guiding the ship through obstacles. Do not select a faster speed than you are comfortable handling.

Missile
The Missile power-up can be selected two times. The first time you select it, the missile launchers will be activated,  The second time you select it, the missiles that you launch will fly faster. When you activate the missile power-up, your ship (and every Option that follows it) will launch two missiles. If the screen is scrolling horizontally, the missiles will launch upward and downward, while if the screen is scrolling vertically, the missiles will launch left and right. The missiles continue to travel until they fly off the screen, or until they land on the surface of some terrain. They will continue to coast along the terrain as long as the terrain is flat or slopes downhill. They will explode if they come into contact with an enemy, doing enough damage to destroy most basic enemies.

Ripple
Since the ship's missile systems now fire in two directions, the Double weapon technology has been replaced with the Ripple Lasers. The ripple Laser fires an energy ring that streaks from one end of the screen to the other. As it travels along, it actually expands and grows, making it far easier to hit enemies at a distance than those flying up close to the ship. The Ripple Lasers cannot be activated simultaneously with the regular Lasers.

Laser
The Laser power-up can be selected two times. The first time you select it, Lasers will be activated,  The second time you select it, your Laser will become more concentrated and stronger. The upgraded cyclone laser has a much thicker beam, but travels across the screen slightly slower. The beam can be extended a short distance by holding the fire button down. The beam will travel up and down with the height of its originator, even after the beam terminates and flies forward on its own. The beam will strike any enemy that it hits, usually destroying any basic enemy that it comes in contact with. As mentioned above, you cannot activate the Ripple and the Laser at the same time.

Option
By collecting an option, you essentially multiply the fire power of your ship. If your ship powers up, so do your Options. Options are primarily used to increase your offensive power, but they can also be used to safely destroy objects in positions that the ships cannot survive. The Options typically follow your ship in a snake like way, trailing behind in the ship's previous positions. Small adjustments to the ship's position causes the options to similarly adjust themselves. Between both players, you can only activate up to a maximum of two Options in the North American version and three Options in the Japanese version. That means if one player has two options, the other player may only have one in the Japanese version, and none in the North American version. However, when one player dies, the Options become freely available to the first player who touches them. The enemies attack you with a firepower that is proportional to your perceived threat. Therefore, the more Options you have activated, the more aggressively the enemies will attack you.

''Note: The extra Option that the Japanese version allows for comes at the cost of greater on-screen flickering. It is unknown if the North American version reduced the number to reduce flicker, or to keep it consistent with the rules of NES Gradius.''

Force
The Force field in NES Life Force does not follow the traditional Gradius Force Field, but rather it introduces the glowing field which surrounds your ship. It can absorb a large number of enemy bullets and collisions. The glowing Force field shows no sign of weakening, making it difficult to determine how much more damage it can take. Eventually, it will disappear, indicating that the benefit of the field has ended. Unlike the original Force Field, this field can effectively block attacks from all directions.

Power-up Strategy
Choosing which power-ups to take, and in what order, is an essential part of the strategy when playing Life Force. Choosing the best selection depends on your playing style and the stage that you are about to encounter. In general, you should aim to have one Speed-Up, one Option, Lasers and Missiles by the time the pre-stage portion of the stage is complete, which is 12 capsules altogether. If you are prone to getting hit by enemy bullets frequently, you may wish to substitute the lasers with a shield, although this will cut down on your offensive capabilities until you can amass the four capsules needed for lasers.
 * When starting off with no power-ups, it's a good idea to start with one Speed-Up. This allows you to fly quickly between the different heights that power-up capsule providing enemy formations will appear at, but it's not necessary if your timing is very tight.
 * Opting to activate the laser right away can cut down on the amount that you need to fire, or even how fast you need to arrive somewhere, in order to destroy an entire formation and collect a power-up capsule.
 * Activating at least one Option early on can also significantly enhance your firepower during the pre-stage portion of battle.
 * Selecting missiles is important once you arrive at the terrain portions of a stage, and may be put off until that time, although you may find it useful to destroy enemies during the pre-stage as well.
 * Do get the second missile power-up early on. Do not get the second laser power-up until you have everything else you want.

You should choose the Ripple power-up rarely, if ever, as it simply isn't as effective a weapon as the lasers. It is a fast weapon and has it's uses, especially when you are attempting to hit a large number of weak enemies across a large open expanse of space, but such times do not occur very frequently. The Ripple laser is also quite difficult to use against enemies that take multiple hits to destroy.