The classic edition of Avalon Hill's Gettysburg had an impact all out of proportion to its its quality -- it was the first. First published in 1958, Gettysburg was the first historical board wargame. Prior efforts like Tactics and just about every other previous military-themed wargame were either based on fictionalized settings or merely used a historical topic for inspiration
Charles Roberts' Gettysburg, on the other hand, was an attempt to model an actual historical battle with an authentic order of battle fighting over a map of the actual terrain. This game basically inaugurated the historical board wargame hobby.
That's not to say that the game doesn't have some serious shortcomings. After starting off with a square-gridded map, the game took a brief detour to hex-based before returning to a square grid in the 1964 edition, which is the version reviewed here.
Gettysburg's retro move to squares aside, hexes were the wave of the future, to the point that board wargames are commonly referred to as hex-and-counter games. Squares have significantly more distortion than hexagon grids, so Gettysburg is unusual in that respect.
The game's counters are also unusual by being rectangles instead of the typical squares. Each unit has the usual combat strength "factor" and movement "factor," but also has a directional arrow showing the facing. Rectangular counters would be unusual for many years, although more wargames have used them recently.
Although a simple game, Gettysburg has some fairly involved facing rules for that era, with attacking units getting a bonus for attacking from the side or rear.
The game uses the classic 3-1 D-elim CRT seen in many other Avalon Hill games ( By my count at least 8 games used it).
As history the game isn't all that great. The lack of any sort of morale or command control rules (headquarters units have no game function) means that the opposing armies are far more active than their historical counterparts, so the game will be played to a decision in much less than the 49 available turns. That decision is an unusually brutal one for a wargame victory condition -- total elimination. No victory points. No geographical objectives. No morale targets. Nope, it's last man standing wins.
There was considerable debate back int he 60s over which side was favored to win. The Confederate player has the usual Gettysburg battle advantage of more powerful units, while the Union player has more units. Handled well (and with good luck), the CSA can defeat the Union troops in detail. A few missteps or bad die rolls and the Union numbers start to tell. I don't think a final answer was had before players moved on to more realistic wargames, including a couple dozen on Gettysburg itself.
There's very little reason to play the game today. Like most of the AH classics outside of the possible exception of Afrika Korps, Gettysburg is mostly of interest to collectors now.