What is Diplomacy?
Diplomacy is a strategic tabletop game about war in 1901.
How do I play Diplomacy?
You can play on websites, in-person, or on tabletop simulator. As websites only let you make legal moves, and the in-person variant is expensive, this guide will go over the rules and format for playing it in tabletop simulator.
In tabletop diplomacy, orders are written on notecards. This can make the game slightly confusing, as it is not always obvious how orders will resolve or how to format your orders.
Generally, formatting looks like this:
[fleet/army] [place starting] [action] [place going/relevant orders]

In this example, France (teal) is holding Spain with two units supporting it. Italy (green) is attacking Spain at its Southern coast, but does not have enough units to overpower the units holding Spain. The orders of each side would look as follows.
France orders:
Army Spain hold
Army Gascony support hold Spain
Army Marseilles support hold Spain
Italy orders:
Fleet West Med. Move Spain
Fleet Gulf Lyons support move West Med. to Spain South

In this example, Italy is invading Austria's (red) border, with some help from Germany (black). Germany's order to move to Vienna cancels the order of the unit in Vienna, therefore leaving the unit in Trieste on its own, to be defeated by the invading Italian units.