I remember getting floppy disks in magazines, I've used cassette tapes with a Commodore 64, I also remember flexidiscs for music, but I've never heard of the flexidisc as a software medium. Where was this?

I found a reference to a Thompson Twins game distributed by flexidisc in the UK.

They would come in computer mags. Byte, Compute, Creative Computing. Hobbyist magazines. You had to record them to your cassette drive first.