This War Without an Enemy is a 2-player strategic block wargame set during the first English Civil War, when the Royalist forces fighting for King Charles I were opposed by the English Parliamentarian troops and their Scottish allies, the Covenanters, in a struggle for political, economic, and religious control of England.

The game engine resembles the typical mechanics of a card-driven block wargame, but it adds a number of innovations in order to faithfully simulate both the warfare of the mid-17th century and the unique nature of this conflict. Every player has their deck, and the card decks are adjusted from year to year to reflect the historical progression of the war.

The battles are resolved on a Battle mat and the conflict is recreated using a system of Leader and Regional blocks as well as rules for regionally-based recruitment. The usual block game mechanics for field battles have been modified with special rules for artillery, cavalry, and infantry, while a completely new system has been designed for storming and sieges.

The object of the game is to acquire Victory Points during the five available scenarios through the capture of cities held by the opponent, while the Parliamentarians can move closer to victory by capturing the King.