Life Force (also known in earlier Japanese and European versions as Salamander) is a sci-fi shoot-'em-up developed and released by Konami in 1986.
A spin-off of the 1985 game Gradius, Life Force puts players back in control of the starfighter Vic Viper (known in the NA version as U.S.S. Light Speed) as they either repel an invasion of the planet Latis from the Bacterion cluster's Salamander Army (in the earlier JP and EU versions), destroy a brain tumor in an infected massive half-human half-biomechanical warrior named Sentinel XR1 (in the NA version), or destroy mysterious super-organism "Life Force" (in the later JP version).
While similar in gameplay to the original Gradius, Life Force is different due to its lack of a checkpoint system (with players respawning in the same area), two-player synchronous multiplayer, both side-scrolling and vertical-scrolling stages, and a new power-up system (where enemies drop power-ups directly). Certain versions of the game, notably in the later Japanese version, reverts back to the standard Power Meter system of the original Gradius.
The Salamander version and both Life Force versions have numerous differences due to their altered story. Taking place inside a giant organism, both Life Force versions replaces the backgrounds of certain stages (from vast starfields to more organic environments) and add additional voice samples and text.
The Salamander version of the game received multiple ports, re-releases, and a dedicated sequel. All versions were included in multiple compilations.
Players start each life with minimal speed and a basic cannon shot, and can upgrade their ship by collecting power-ups dropped by certain enemies.
In the later Japanese version, the game uses the Power Meter system from Gradius, in which players collect Power Capsules to progress through their six-part Power Meter. Each Capsule progresses through the highlighted parts of the Meter, which determines which power-up players get once they hit the Power-Up button (after which it empties). Collecting a Cell while the meter is maxed brings it back to the first highlighted part (Speed-Up).
These power-ups are, in Power Meter order:
- Hyper Speed / Speed-Up: Increases the ship's movement speed. This can be activated multiple times to further increase the speed, although higher levels can be very unwieldy.
- Missile: Allows the ship to fire missiles in both directions perpendicular to the ship. If the missiles reach a flat surface, they move along it until it reaches an enemy or a wall.
- Laser: Replaces the Vic Viper's cannon with a more-powerful laser cannon that overpenetrates enemies. Replaces the Pulse Laser power-up.
- Pulse Laser / Ripple Laser: Replaces the Vic Viper's cannon with a more-powerful laser cannon that widens over time. Replaces the Laser power-up.
- Multiple / Option: Creates a ball of energy that follows behind the path of the ship and fires the same weapons (and missiles, if active) as the ship. In most versions of the game, this can be activated up to four times, each of which creating a new energy ball. In two-player games, each ship shares two energy balls.
- Force Field / Shield: Negates projectiles that hit the ship. It has limited energy before it depletes.