Hi,
As the title says, I am trying to find out what was the very first 'planet defender' type game. It is a well used formula on Itch, a planet in the center of the screen with an orbiting ship that shoots outwards to blast incomming asteroids and spaceships. It seems like it is a variation on the Asteroids arcade game from the late 1970s/early 1980s but I can't find any such arcade games from that era. The planet defender games that do come up from a Google search are all fairly recent.