X (エックス, Ekkusu), is an early three-dimensional first-person shooter-type video game software released for the Game Boy only in Japan on May 29, 1992. The game was published by Nintendo and was developed by Nintendo R&D1 alongside Argonaut Software (who later became known for the original Star Fox title for the Super NES).

X was followed by an internationally released DSiWare exclusive sequel, X-Scape.

The game takes place in a wire frame 3D view. The player controls the VIXIV to complete various missions assigned by the Training Academy Coach. Objectives can range from destroying enemy targets, escorting cargo, or defending bases. A short break is provided after the completion of each mission, and the player is awarded a number of stars based on their skill in each level. 10 small stars equal one regular star, and a certain number of stars are needed to continue the game after failing a mission. The game is completed by finishing all ten missions.

Controls

Pressing the A button shoots a laser beam, which is the most basic form of attack in the game. The beam is shot towards the crosshairs at the center of the screen when no targets are present. When a target is within a reasonable distance, an aiming cursor appears, and the beam will always hit the target indicated by this cursor. Most objects can be destroyed with a few laser shots, but objects that emit a metallic sound when hit cannot be destroyed with the laser. Pressing the B button uses the more powerful weapon equipped at the radar base.

Enemies and objects will sometimes leave behind a powerup or item when destroyed. These are automatically picked up by the tank's tractor beam when the player moves nearby. The specific target needed to complete the mission can be located with the finder. This is a white arrow that appears at the bottom of the screen, and moving forward with this arrow at the center will always lead the player to the specific target.

The grid on the lower right hand corner is a simplified map of the entire level. The map shows the player's current grid location, previously visited areas, and radar base locations. In certain missions, some parts of the grid will flash to indicate the location of nuclear silos or radar bases that are under attack. The planet Tetamus 2 consists of a rectangular map, divided into 8 areas, which are useful for tracking down specific enemies or buildings. If a player moves across an edge of the map, the tank will emerge from the opposite side of the rectangle. Pressing the START button will pause the game, and show a more detailed map of the planet.

The map contains four entrances to underground tunnels which can be used to move between areas without having to encounter enemies. If the mission has a time limit, the clock stops while the player is moving through any of these tunnels. However, hitting a tunnel wall will damage the tank's shield. The player can still move forward will hitting tunnel walls, but running into a chain link fence will cause damage and force the tank backwards, so a certain amount of caution is needed while proceeding through. Speed cannot be increased or decreased in the regular control scheme while traveling underground, but grinding the tank against the ceiling will cause a slight decrease in velocity, while grinding it against the floor will cause a slight increase in velocity.

The VIXIV also has flight capabilities. Lifting off one of the pyramid-shaped objects at TURBO speed will send the tank into the air. Speed cannot be adjusted while the tank is in the air, and flying requires fuel. Some of the field objects located at ground level will fade away from view while the tank is in flight.

The controls for the game are highly sophisticated and difficult to master, so a training mode is provided to familiarize the player with the controls. The training mode devotes a mission to each basic skill, and is so extensive that the player will have naturally learned the controls upon completion of all of the training missions. This allows the player to learn the basic controls quickly and efficiently without having to use the instruction manual. The actual game cannot be played without completing this training mode first. If the player has previously completed every training mission, an option is given to proceed directly into the actual game or review the basics in the training mode.