Inis is a game deeply rooted in Celtic lore and history in which players win by being elected King of the Island (Inis). Players can try to achieve this via one of three different victory conditions:

• Leadership: Be the leader — i.e., have more clan figures than all other players — of territories containing at least 6 opponents' clans.
• Land: Have your clans present in at least 6 different territories.
• Religion: Have your clans present in territories that collectively contain at least 6 sanctuaries.

Over the course of the game, players also earn deeds, typically chanted by bards or engraved by master crafters, that reduce by one the magic total of six for any condition. While one victory condition is enough to claim the title of King, a game of experienced players usually has a tight balance of power, emphasizing the leadership of the capital of the island.

At the start of every round, players draft a hand of four action cards during the Assembly. Action cards that are not played at the end of one season are lost. Also, players have access to leader cards for the territories that allow it and where they were elected leader during the assembly. Each Assembly reallocates those cards. Finally, players collect "epic tales" cards that depict the deeds of the ancient Irish heroes and gods, like Lugh, Cuchulainn, the Dagda, and many others. These will be kept and used to inspire the clans and achieve extraordinary feats when the right circumstances arise. The cards provide a variety of actions: moving clans, adding clans, building/exploring, and special actions.

Careful drafting, hand management, good timing, bluffing (especially once players understand the importance of passing their turn), and a precise understanding of the balance of power are the keys to your victory. After a discovery-level game you'll be ready for a full and epic game, where an undisputed player will be king by the Assembly for his wisdom and merit.

While Inis has "dudes on a map", it's a beginner's mistake to play this as a battle game because simply eliminating other clans reduces your chances of scoring a Leadership victory condition. Peace among different clans, with or without a territory leader, is the usual outcome of a clan's movement. Battles will occur, of course, as the Celtic clans can be unruly and a good player will listen to their clan's people (their hand of cards). That battle aspect is reflected in the clan's miniatures representing warriors. Shepherds, woodsmen, and traders complete the set of twelve minis for each player; these occupations have no impact on the game, but give it flavor.