gRPC API

Documentation for the gRPC API exposed by Age of Empires II: Definitive Edition (AoE2DE) during replay playback, as reverse-engineered by the LibreMatch project.

Overview

AoE2DE exposes a gRPC endpoint when watching replays. This allows external tools to receive game state updates in real-time without running the game simulation themselves. The API streams delta patches representing frame-by-frame state changes, along with game events and player commands. It is used by CaptureAge for spectating.

The protocol buffer definitions and format specification documented here are the result of reverse engineering the *.caderec format as part of the LibreMatch delta-play-replay project.

Protocol Buffers

The API is defined using three proto files:

• CadeRemote Service (cade_api.proto) - The main gRPC service with RPCs for game info, pause control, fog of war, perspective switching, and frame streaming
• Atlas Data (atlas_data.proto) - Sprite and asset information for rendering
• File Metadata (file_metadata.proto) - Metadata for graphics files

Delta Play Replay (DLPR)

delta-play-replay is the LibreMatch project for creating a specification and tooling around a new open replay format (*.dlpr) for AoE2DE, based on the reverse-engineered *.caderec format:

• Delta Patch Format - Specification of the stack-based delta patch format used in frame data
• DLPR Requirements - Requirements analysis for the new replay format