It was another time.
However, for computers, there are good cosims both with traditional hexes and without (vector-based, and simulation based) today, with AI and all you can desire. Even my beloved Steel Beasts can be played from map view, as a cosim, exclusively. Regarding classical cosims, there also were some titles that were specially designed to be played alone. Ambush! on my mind, or Tokyo Express, which I have reviewed here at subsim some years ago. You can find it in the reviews section, I assume. Very elegant game design, imo: simple, but allowing surprising depth. In that game, single play was the rule. Playing against another player was the option that required "modded" extra rules.
Always liked that kind of games. Playing these wargames in Germany of that time, however, earned you critical views and angry comments. Difficult to find opponents and coordinating time and space options with them.