In 1989, the first Sierra game I ever played, Space Quest III, shipped on six 5.25-inch double-density, double-sided floppy disks. A hard drive was optional, though copying the game files to the HDD substantially improved performance. The total game install was between 3.5 and 4MB–but that was significant, when a computer from the same time period only had between 10 or 20MB of HDD space.
https://www.extremetech.com/gaming/256790-game-installation-sizes-still-exploding-upwards
https://www.extremetech.com/gaming/256790-game-installation-sizes-still-exploding-upwards