I started roleplaying with Runequest 2 and AD&D 2e back in the 80's, and haven't stopped since.

I've also played RuneQuest 3e, Traveller 1e, Call of Cthulhu 1e, Pendragon 3e/4e, Microscope and Ars Magica 3e, 4e & 5e, as well as dabbling in other RPGs too numerous to count, too fleetingly to remember right now.

I am an avid world builder, and have drawn multi-layered maps and written hundreds of pages of setting detail for many worlds including an Ars Magica 4e -based high-magic campaign with multiple tetrahedral worlds of varying sizes, set in an air-filled crystal sphere.

The campaign I am currently running is a science-fantasy campaign based on Ars Magica 4e rules, set in a universe where stars and galaxies are connected by mysterious air-filled conduits. It currently has on the order of a dozen worlds (including our own, with alternate/additional history), many with detailed history (going back up to - or even over - 10,000 years BP) and society write-ups, as well as alien species, multiple magic systems, and (perhaps overly) detailed rules (complete with Excel workbooks) for constructing ships, aircraft and mecha.