When I started Frontier I thought that a game doesn't have to stay in a certain time period, this is what I meant.
This expansion is here to add to the Frontier experience by adding additional time periods and content. This expansion will include WW2, The Vietnam War, The Gulf War, and if it's even possible, The American Civil War. Until this is updated again, check out the regular Frontier homepage at moddb.com/games/frontier
Sincerely,
The Frontier Team