Solium Infernum is a strategy game where the player vies for the control of Hell against other archfiends (up to five). The previous Prince of Darkness has mysteriously vanished and the throne longs for its new master. You can become the new ruler in three ways: win the favor of the Infernal Conclave by gathering the most prestige points before the predetermined number of Conclave tokens are presented by the game, manipulate the High Conclave right before the election or conquer the Pandemonium, Hell's capital, and keep it and your stronghold under control for five turns. Everything takes place on a hex-based map that wraps into itself, allowing the player that scrolls in a single direction to eventually arrive at his starting point.
Besides the turn-based mechanics, two gameplay factors are the most important: gaining prestige and having powerful armies. You gain prestige by controlling regular territories (Cantons) and Places of Power, completing the objectives you personally selected, winning battles, acquiring specific relics, succesfully using destruction rituals and winning diplomatic conflicts. The Bazaar is the place where you can buy new legions, praetors, artifacts, relics and manuscripts. Praetors can be placed in your strategic points, such as your stronghold, in order to strengthen their defenses. They can also be used as champions in diplomatic brawls. Artifacts can enhance a legion's stats, while relics and manuscripts offer additional bonuses.
Tribute cards are the game's official currency, which you use to buy the things you need. You get these cards by demanding them from your minions every turn. This and every other action, such as raising your attributes occupies one of the order slots, the number of which is limited. Your freedom of action can also be restricted by all archfiends (including yourself) when they start an event, for example the excommunication of an opponent.
Solium Infernum offers two single-player (Normal Game and Iron Man, which restricts your save opportunities) and two multiplayer modes (Play-by-Email and Hot Seat). When starting a new game, the player can customize a series of options, like choosing a map and its size, the number of opponents, objectives etc. At the same time, if he doesn't like the default avatar (Abaddon), in the Main Menu he can create a new one with the wanted attributes and demonic rank.