Gloomhaven is a series of tactical combat scenarios that are strung together in a persistent, thematic campaign.
Each scenario is played out through rounds of combat against fully automated enemies. In each round, players will play 2 cards to determine the order in which they act and what abilities they perform. Each card has 2 special actions, and on their turn, players can perform the top action of one card and the bottom action of the other.
Card actions are varied and powerful, cutting through the monotony of a basic "move and attack" system. Default actions are available, though, if a player's plans get ruined by an enemy's ability card or even by the actions of their own teammates. Gloomhaven eliminates the alpha player through simultaneous hidden action selection to illustrate the chaos of battle.
There are also no dice in Gloomhaven. Instead, attacks are modified by a player's attack deck. Over time, this attack deck will change as a player begins to add and remove cards by completing battle goals and leveling up, which will also give them access to more powerful, higher level ability cards.
In midst of battle, players will also need to focus on looting money tokens. These can be used to purchase useful items in town, where new stock is always being unlocked by player actions.
As players interact with the town through events and move along the branching story paths of the world, they will always be working towards completing personal quests. By meeting certain objectives, a player's character will retire, unlocking a new character class to play with, new events for parties to encounter, and additional perks for the achieving player. After retirement, a player will create a new character, possibly from the class that was just unlocked, and continue the adventure!