The follow-up to Sid Meier's Gettysburg!, Firaxis Games' tactical real-time wargame set during the American Civil War, Sid Meier's Antietam is a direct sequel developed by BreakAway Games and released late in 1999. As its forebear did, Antietam! recreates a single battle in the war, in this case the Battle of Antietam, the bloodiest one-day battle in US history. Both mechanically and visually, it is extremely similar to the previous game, and aside from its shift in focus to a new venue, which brings with it many new scenarios as well as a new campaign, the changes made to the Gettysburg! formula are decidedly subtle. Antietam! incorporates new interface elements, additional terrain and unit types, as well as introducing higher potential experience levels and command ratings for troops and commanders. Refinement is the common theme with most of these changes, as Antietam! chooses not to reinvent but rather to streamline the original Gettysburg! experience.
In what was an unusual move at the time, Antietam! was not available at retail like its predecessor, instead being sold only through the Firaxis website. Firaxis' original plan was for Antietam! to be the first installment in the Sid Meier's Great Battles Series, a procession of stand-alone releases based on the Gettysburg! engine each dealing with a single battle in the war. They were to then be directly marketed and sold to the Gettysburg! online community through the Firaxis website, where they could be purchased at a reduced price. While Antietam! was the only independent product to be born of the Great Battles Series, Sid Meier's South Mountain! was later distributed as a patch for Antietam!, and was also included in the Sid Meier's Civil War Collection.
See also: Sid Meier's Gettysburg!
The basic structure of Antietam!'s individual scenarios does not differ overmuch from that of Gettysburg!. Engagements last a finite amount of time, and at their endpoint the winner is decided by way of Victory Points (VP), which are awarded both for casualties and holding objective points, with the latter usually being the more important of the two. By contrast to the individual missions, the Antietam! campaign dramatically diverges from the previous game's format. Whereas Gettysburg! presented its campaign as a series of linked scenarios which could branch in different directions based on the player's performance from one to the next, the sequel reenacts the Battle of Antietam as a single lengthy scenario, with additional variant campaigns which alter certain parameters. This particular change was a point of contention with some reviewers, though, who felt that the style of Gettysburg!'s campaign, as well as the atmospheric briefings that accompanied it, was far superior. Although not strictly related to gameplay, Antietam! also includes the formerly-unpublished Antietam battle report of Union officer Ezra Carman, which can be accessed and read from within the game.
Antietam! updates the Gettysburg! engine modestly in both mechanical and graphical capacities. A greater visual variety among troops is present, which is complemented by additional regiment types like Sharpshooters and Zouaves. Additional types of artillery are also present, and canister shot is also available to them for use in close-range scenarios. Antietam! also introduces a sixth experience level for troops, Elite, which starts regiments with a baseline of six blocks on their morale bar, and a fifth level of command rating for superior officers, Legendary. New terrain features such as corn fields and sunken roads further bolster environmental variance, and water features can now only be crossed at bridges and fords. The game's user interface was slightly altered in order to incorporate newly-added features or to streamline existing ones, and Antietam! includes a greater number of contextual tutorial pop-ups as well in order to help ease new players into the game's concepts.
The reaction to Sid Meier's Antietam! was generally positive, although noticeable less enthusiastic in some cases than the reaction to Gettysburg!. Comments regarding gameplay were perhaps the most unequivocally favorable, as it was frequently noted that Gettysburg!'s tactical real-time mechanics, with their heavy emphasis on formations and troop placement, still held up with the release of the new game. The updates to the game's mechanics and its new scenarios were both seen as significant assets as well, though the lack of a dynamic campaign was lamented by some. Certain individuals also seemed appreciative of the fact that a number of the more commonly-highlighted ease-of-use issues and interface quirks of the previous game had been fixed or at least addressed with the release of Antietam!.
One of the most common complaints leveled against Antietam! was that, while solid, it was still a fairly typical sequel which neither significantly expand upon the foundation of its predecessor nor went out of its way to draw new players in. And while it was generally agreed that the Gettysburg! formula had aged well, the same was not always said for its presentation. Several reviewers recounted experiencing severe slowdowns during larger battles, and while most felt that the game's graphics were still attractive or at least serviceable two years later, others expressed concerns that the aging technology of Antietam! would limit the game's appeal outside of existing Gettysburg! fans and wargaming advocates, with a few even openly calling for a new engine if further titles were to be seriously pursued.