One of the greatest (and coolest) video games I ever played on my old Atari 800 in the 1980's was Mike Edwards' Zombies (BRAM Inc; 1983), later re-released by EA in 1984-1985 as Realm of Impossibility.
This game was available on both cassette (!) and floppy disk, but my memory is that I played the game on disk. It was so long ago now, I'm not entirely certain about that detail, however.
They had titles like Blue Max, Trains, Murder on the Zinderneuf, Bruce Lee, Astro Chase, B.C.'s Quest for Tires, Caverns of Mars, and last -- and best -- Zombies!
Designer Edwards was inspired in part by his love of TSR's Dungeons and Dragons, as he wrote in the marketing booklet for Zombies. But he also wanted to get away from simple shoot-em-up games of the era. Thus he devised Zombies with a few diabolical and genius twists.
Zombies also featured, according to the promotional material: "3-D graphics, on-line instructions,"..."74 different screens, high-score save to disk, full sound and color, zombies, poisonous snakes, giant spiders, evil orbs, scrolls, talismans, magic spells, lost crowns and spectacular underground scenery."
The graphics may look primitive today, but the game play was absolutely incredible.
Makes me miss my Atari 800...