Here are several forms of media used for storing computer games...
1: Cassette tapes could hold up to 660 kilobytes using the Kansas City Standard (KCS) Some of their savvier users have since learned how to copy the data onto a CD and use that instead.
2: Cartridges were used by most consoles, and their capacity varied. The last console to use cartridges was the Nintendo 64, but they are still used on handhelds.
3-5: Floppy disks had a capacity varying from 360 kilobytes on the earliest 5 1/4 inch disks to 1.44 megabytes on 3 1/2 inch disks.
6: Hard disks are used on PCs, Macs, and some modern consoles.
7: CDs were the biggest game-changer to ever affect gaming as we know it! Room for greatly improved audio and graphics finally made gaming popular.
This photo was taken at the Computerspielmuseum