Below I'll catalogue the central elements of this genre; the ones in bold I think are essential, the other just typical.
|Photo by j.mccracken at boardgamegeek|
Hexagonal map grid. Although this was typical of games in that era, there were some games (like the Elric one, or Greyhawk Wars) that dispensed with this, using movement by areas instead. Arguably, you don't really need the kind of precise rendering of maneuvers and battlelines that hexagons give when gaming large-scale pre-conscription warfare, in which small armies cruised across a huge landscape without much operational subtlety, and clashed at designated battlefields.
|Photo by Richard Maurer at boardgamegeek|
The counters represent armies as well as individuals ... Without the armies, it's not a wargame, but an adventure or quest game (as in Greg Stafford's King Arthur's Knights). Without the individuals, it's not epic - typically, one of these games would have rules for heroes leading armies, as well as going on quests, conducting diplomacy, and other things that armies can't accomplish.
.. and there is a lot of flavor and color through other means. Counters for monsters, artifacts, special locations; cards, tables, or numbered paragraphs representing events, nations to be won though diplomacy, relics ... all of these are very typical of the genre and helped give each game the special flavor of its world.
With all these elements, the play and objectives of one of these games were fairly similar to the historical equivalents. Armies fought by comparing strengths and a die roll on a chart, and the object of the game was to capture territory; or at least doing so won victory points. Less typical, though, was the "epic" layer in which heroes moved around the board attempting various things, gaining magic items and allies, which in turn could serve as an alternate victory condition or contribute to victory points.
In the next post I'll attempt a catalogue of these games, and ask for your help in identifying any I may have missed.