R-Type Leo is a 1992 horizontally scrolling shooter arcade game developed by Nanao and published by Irem. Only released in Japan it is the fourth game in the R-Type series.
While somewhat canon, the plot deviates from the original story line: Mankind find themselves at a financially and technologically peaceful state between the constant conflict against the Bydo Empire. A space project called Project Paradise that had been held back for a long time was finally seeing light. The project involved the construction of an artificial terrestrial planet called Eden as a possible Human retreat. However, after the construction and functioning of the planet, Major - the bio-computer system responsible for maintaining Eden - malfunctions, takes control of the planet's defenses and attacks mankind. It is now up to the recently developed R-9 variations, the Leo, to fly in and stop Major's assault on its creators.