I've run a few Mythic Earth adventures using Mythras, and I'm a few months into a Mythic Britain campaign, using the supplement of the same name, which started with the "Waterlands" adventure, an excellent Celtic mystery-horror scenario set in the fens of the north east coast of England. Mythic Britain is set around 500 CE and is more of a Bernard Cornwell style than Excalibur, even though Arthur, Merlin and Morgana are knocking around this time though as dark ages Celts. British druidism is represented using the animism magic system, with the Annwn otherworld being accessible to druids (only) and magic the province of spirits. Early Christians can venerate saints but only very rarely successfully call on Miracles.
Looking forward to Bronze Age Mythic Babylon (during Hammurabi) which is looking very good, due out sometime in 2021.