Age of Empires: The Conquerors - Savegame File Format
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helper AI helper, Wall, Flare May 22, 2013
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spec More actions. Dec 10, 2017
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README.md

Age of Empires 2: The Conquerors — Savegame File Format Specification

Table of Contents

Structure Definitions

The structure definitions kind of follow the BinData Ruby Gem declarations. They should be as readable as pseudo code though. More information on BinData can be found here.

Synchronization

Tag Description Validated
SYNCH

Messaging

Tag Description Validated
0x000001F4 GAMESTART
0xFFFFFFFF CHAT +

Gameplay Actions

Tag Description Validated
0x00 ATTACK +
0x01 STOP +
0x02 AI_PRIMARY +
0x03 MOVE +
0x0a AI_MOVE
0x0b RESIGN +
0x10 WAYPOINT +
0x12 STANCE +
0x13 GUARD +
0x14 FOLLOW +
0x15 PATROL +
0x17 FORMATION +
0x1b SAVE & EXIT
0x1f AI_COORD +
0x64 AI_TRAIN +
0x65 TECH +
0x66 BUILD +
0x67 MULTIPURPOSE
0x69 WALL +
0x6a DELETE +
0x6b ATTACKGROUND +
0x6c TRIBUTE +
0x6e REPAIR +
0x6f UNGARRISON +
0x72 GATE +
0x73 FLARE +
0x75 GARRISON +
0x77 TRAIN +
0x78 RALLY +
0x7a SELL +
0x7b BUY +
0x7e RELIC +
0x7f TOWNBELL +
0x80 BACKTOWORK +
0xFF GAMESTATS UP only

FAQ

  1. What actions are not saved but only calculated on replay simulation?

    • Only actions that are actively taken by players are stored
    • Any other actions are either simulated during replay (map reveal) or determined by the random number generator (Gaia movement)
    • Pause is not saved, that is why chat messages that were sent during the pause are displayed nearly at once when replayed.
  2. What actions are only saved for certain players, i.e., the owner of the recorded game?

    • Viewpoints (for lock view) are only saved for the owner of the recorded game, together with the sychronization info.
  3. How does AoE2 create an .mgx file?

    • Singleplayer games are recorded by getting actions from the input buffer and writing them into the .mgx file.
    • During multiplayer games, actions are distributed to all players (even messages). The input buffer is transferred over the network to the other players.
  4. Why are there so many zeros in the actions?

    • Most of the zeros are caused by memory alignment. Because networking and recording directly work on the input buffer, the data is aligned to 3the size of (menory) words (4 bytes). Example:
    struct example {
      uint8_t player_id;
      uint32_t unit_id;
    };

    Here the first variable player_id will take up 1 out of 4 bytes of the first word. The next variable, unit_id, doesn't fit into the first word anymore, so it will use a second word instead. The remaining 3 bytes in the first word remain uninitialized and therefore have zero values in them.

  5. Why are they doing this weird memory stuff? It sounds stupid

    • Because it is fast. Data can be put to use directly and does not have to be parsed.
  6. What are the various IDs used for?

    • Players have an ID and a number. This is necessary because of an undocumented cooperative mode in AoE2, where players can have the same player number.
    • Unit IDs reference a type of unit/building or object in the game files.
    • Object IDs reference a specific object during a game. Every building, unit or resource gets an ID. For new units, the IDs are incremented.