Gameplay in Chronicle X alternates between two types of segments: the Missions (in Conquest Mode called Conflict Phase) and the Global Operations Phase.
The Mission segment is where most of the gameplay time is spent, and it's essentially a tractical wargames ("dudes on a map") played on a variable Mission Map that is assembled differently in different cases. In the Narrative Mode, the Mission Book describes how the Mission Map should be put together for each Mission. In the Conquest Mode, building the Mission Map is done by the players.
During the Mission, gameplay alternates between the Hero Player Phase and the Overmind Player Phase, until one side has reached their Mission objective.
The Global Operations Phase is the time between the Missions; most of the gameplay here is for the Hero Players, although the Overmind Player will have to decide what kind of aliens to deploy in the upcoming Mission.
Mission
Most of the gameplay time in Chronicle X is usually spent playing Missions, which is essentially a tactical combat game ("dudes on a map").
Mission setup
Before a Mission can start, it needs to be set up. This usually involves building the Mission Map from Map Tiles, and placing Item (Spanner), Hazard and Door tokens on the Mission Map.
In Conquest Mode, the Mission Map is built by one or both players, depending what type of Mission they are playing next.
In Narrative Mode, the Mission Book describes how the Mission Maps should be built. Often, the Mission Book specifies at least some of the Map Tiles to use by code name (a letter, or a digit, or a combination of a letter and a digit). Map Tiles not specified by name are chosen randomly from among Map Tiles with similar background art, when possible.
When the Mission starts, the Hero Players choose two Yellow Squares to use as their deployment points, unless the scenario has already decided which Yellow Squares should be used for that purpose. Then the Hero Players place two of the Heroes on each of those Yellow Squares, and then place the other Heroes on Squares that are Adjacent to the first two Heroes.
Then the Overmind Player similarly chooses Yellow Squares for use as deployment points if the scenario hasn't already made the choice, and places Blip Tokens there. The Blip Tokens may be placed up to two steps away from the chosen Yellow Squares.
Mission gameplay
Gameplay during the Mission alternates between a Hero Players Turn and an Overmind Player Turn.