Daiva 6: Imperial of Nirsartia is the sixth in a series of seven Daiva games released simultaneously on different platforms. Most of the other versions ended up on Japanese computers such as the PC88, PC98 or MSX. The series is not a collection of sequential stories, but rather a presentation of the same story from the perspective of seven different protagonists. There was also a separate comic book and other media released around the same time as part of a massive media blitz to promote the games, all based on the galactic Daiva civilization.
All Daiva games were developed by T&E Soft, which was perhaps best known at the time for the action RPG series Hydlide. Daiva 6 was released by music giant Toshiba-EMI.
The player must explore planetary systems and take control of enemy locations, while protecting his own, just like in Star Raiders. One big difference, however, is that the player is supposed to take control of planets manually by descending onto the planet in a mech. The player can call on three types of support: missiles, which target and eliminate random enemies; bombs, which erase the screen; and a recharge item that recovers health from the player mech. The player chooses where to drop these power-ups at what points in the level before entering it, which requires a certain degree of strategic preparation before the assault.
The action stages are all side-scrolling shoot-em-up action levels reminiscent of something like Side Arms or Thexder. The goal is simply to get to the other end of the stage without losing all of the mech’s shields and without being destroyed. Each stage has a different gravity: on most stages the mech drops to the bottom and the player can apply a small push to slide the mech and jump over enemies and obstacles. Sometimes the gravity is so great that the Mecha is very limited in its vertical movement.
Moreover, the game also has elements of strategy. It has turn-based strategic battles whenever the player’s mothership encounters other spaceships in deep space. The player selects where they want to move/shoot and the round proceeds. Although primitive, Daiva 6 has one of the earliest examples of the TBS genre, which would eventually become very popular on the Famicom and other Japanese computers.