Dominion is an empire-style multi-player world simulation game. Each player is the leader of a nation, and makes decisions for that nation. The decisions are political, military, diplomatic and economic, and all these are extremely important for the well-being of a nation. Some nations can be played by the computer. These nations are called NPCs (Non Player Countries). They play a challenging game, and are quite useful if few human players are available.
Dominion has features from both fantasy role-playing games, educational games, and war games: a user needs to develop a character as leader of a nation, keep a healty economy, and can then develop a strong military force using magic or technology.
Most of the moves you make are not resolved until the end of a turn, when the update is run. This update will incorporate your changes into the world data base, then it will update your economy, handle migration of people, resolve battles and conquest of land, freshen up your armies (restore move points), and a few other things.
The rhythm of the game is set by how much money you have spent, and how much you have moved your armies. If you have spent all your money, you will need to wait until your revenue comes in (after the update) before you can spend more. Similarly, if you have already moved all your armies, and they are overcome by fatigue, then you will have to wait until they have recovered. This will happen in the update. The time elapsed between updates is called a thon.