R-Type III: The Third Lightning was released in 1993 to the Super NES console exclusively. It later ported to the Game Boy Advance and the Wii's Virtual Console. It's usually considered one of the best of the series.
The dark forces of the BYDO Empire threaten humanity yet again, with more
powerful weapons than ever. Over the past few years, they have crept close to
Earth, building hidden bases for their fleets. The Earth Science Center had
believed that all of the BYDO Empire was destroyed. Now they know that
somewhere a BYDO mother ship carries the remnants of that foul civilization.
Earth will be overthrown unless the latest R-series vessel, the R-90, can defeat
BYDO's armies. Equipped with the mighty Round, Shadow, or Cyclone Forces of
power, the R-90 can warp into different dimensions and meet the enemy ships and
ground troops on an equal basis. As the Captain of the R-90, you must seek out
the mysterious mother ship and destroy it to save humanity.
- SNES Manual
After the events of R-Type III, nearly four centuries pass until the next known mission, R-Type Final.
The R-90 Ragnarok has more than enough power for this mission. So powerful, in fact, that it's future version in R-Type Final was reduced in power. Some of its abilities were split amongst other ships.
A notable difference between the Western and Japanese versions is the stage boss at the end of Acid Creatures, in the Japanese version the pilot is attacked at this point by large sperm-like swimming creatures, whereas the other version replaces these with swimming eyeballs that still retain their sperm-like shape.
