Sid Meier's Gettysburg!

The game allows the player to control either the Confederate or Union troops during the Battle of Gettysburg in the American Civil War. It can be played as single scenarios, or as a campaign of linked scenarios, either recounting the original history or exploring alternative possibilities.

There was a large online following when the game was being hosted on Mplayer (a multi-player game network bought by GameSpy industries). After moving to GameSpy, the game dwindled in popularity for online players. At the pinnacle of online play, there were many groups of players. A competitive ladder (league) was also a fixture of this time, where the hall of fame can still be viewed. "Case's Ladder" Online play is now, for the most part, impossible due to the shutdown of GameSpy's servers.

The engine was also used for the Napoleonic game Waterloo: Napoleon's Last Battle (as was a modified version for Austerlitz: Napoleon's Greatest Victory), both by BreakAway Games.

Gettysburg! was a commercial success, with more than 200,000 copies sold by August 1999. At the time, Jeff Briggs of Firaxis commented that the game "did extremely well for us". From critics, it received "universal acclaim" according to the review aggregation website Metacritic.

During the AIAS' inaugural Interactive Achievement Awards, Gettysburg! was a nominee for "PC Strategy Game of the Year", which was ultimately awarded to StarCraft and Age of Empires (tie). Similarly, the Computer Game Developers Conference nominated Gettysburg! for its "Best Strategy/Wargame" Spotlight Award, but gave the prize to Myth: The Fallen Lords.

Gettysburg had a large modification ("mod") community. Players can customize uniforms, maps, sounds, and units. This aspect of tweaking the game proved vital to Civil War aficionados looking for historically accurate models. This ultimately led to the creation of other famous battles such as the Battle of Fredericksburg, the First Battle of Bull Run, the Peninsula Campaign, and more.