> For the complete documentation index, see [llms.txt](https://lionstudios.gitbook.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://lionstudios.gitbook.io/readme/analytics/progression-event.md).

# Progression Event

## Introduction

Progression events help you understand how players move through your game, where they struggle, and what to improve to drive retention.

We use mission events to track both main progression and side activities (for example challenges, side quests, and paid levels). Our data analysts will provide game-specific guidance on what to track and how to structure it.

## Game Events

#### [**`GameStarted`**](/readme/analytics/api/events/gamestart.md)

This event is triggered automatically upon Lion Core initialization to track a number of different metrics.

#### [`FeatureUnlocked`](/readme/analytics/api/events/featureunlocked.md)

Use this event when a player unlocks a level, item, badge, skill, or any other unlockable content.

## Mission Events

#### [**`MissionStarted`**](/readme/analytics/api/events/missionstarted.md)

Fire when a player starts a mission attempt.

#### [**`MissionStep`**](/readme/analytics/api/events/missionstep.md) (Optional)

Fire when a player reaches a significant checkpoint within a mission.

#### [**`MissionCompleted`**](/readme/analytics/api/events/missioncompleted.md)

Fire when a player completes a mission successfully.

#### [**`MissionFailed`**](/readme/analytics/api/events/missionfailed.md)

Fire when a mission attempt ends unsuccessfully.

#### [**`MissionAbandoned`**](/readme/analytics/api/events/missionabandoned.md)

Fire when the player leaves a mission before completion (including restart).

### Required Parameters (all mission events)

* `missionID`: Identifier for the mission/level
* `missionAttempt`: Attempt number for this missionID
* `missionType`: Mission category/type
* `missionName`: Display name (if applicable)

### Implementation Rules

* Each mission attempt should include one opening event (MissionStarted) and one closing event (MissionCompleted, MissionFailed, or MissionAbandoned).
* Use consistent parameters across all events for the same mission attempt so we can accurately match events and calculate metrics server-side.
* Increment missionAttempt each time you fire MissionStarted.


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