Vertical Force is a vertically scrolling shooter, with two layers (to utilize the 3-D features of the system) for Nintendo's Virtual Boy video game system. It was developed by Hudson Soft and released in 1995.
The game takes place in "Space Era 210." The giant computer that takes care of a human colony planet named Odin suddenly malfunctions and decides to send an army of drone starfighters to destroy Earth. These drones emit a signal that renders all Earth starfighters useless. An archaeology team finds an ancient starfighter on the planet Ragnarok that is fortuitously impervious to the drones' signal. It is up to the player to command this starship and destroy all the alien drones.
The player controls a ship whose purpose is to shoot any enemy that enters the screen. Collecting powerups will change the weapon used. By pressing a button, the ship can move into the foreground to avoid or shoot enemies or collect powerups that lie on the ground below. Some boss enemies can only be defeated by cycling between the two fields. An additional gameplay element is the ability to use "drones"; AI-controlled smaller spaceships that assist the player's starfighter. The game has a high-score board, but no battery-powered memory with which to save those scores, so they are lost when the player turns off the Virtual Boy unit.
The game includes several references to Norse mythology.The planet where the player's starfighter is found is called Ragnarok, which is in Norse mythology the large battle at the end of the world. The giant, corrupted computer that is the villain of the game calls itself Mittgard, a play on words for Midgard, which was said to be where all humans lived and in the middle of the tree of life. The name of the human colony is Odin, the name of the Norse supreme god or "all father".