s2protocol-rs

A nom parser for the Starcraft 2 Protocol Replay format. Provides Iterators to transist a minimal state machine through the game loops Keeping track of unit groups, upgrades, targets, etc.

Motivation

The goal is to learn how to parse binary files format with nom and to learn how the Starcraft 2 Replay file is so incredibly small for the amount of information it packs.

From the available data, analytics, visualizations and generative art can be created, for example by using

• jupyter notebook in s2-polars-data-analysis - rerun : See the repo swarmy
• yew cooper
• eframe/egui: See repo eframes-c2
• bevyengine/bevy can be used to see:
  • An Enhanced Replay Minimap
  • Additional statistics.

Consuming events

Transition Iterators

• SC2EventIterator collects both TrackerEvents and GameEvents. Events are provided as they appear, be them Tracker or Game, they are sorted by the adjusted game loop.

Event changes transist a minimal state machine that updates:

• names
• positions
• Attack events
• etc.

The iterators returns a struct of type SC2EventIteratorItem. The event field contains the event itself as it was deserialized from the SC2Replay. The change_hint field hints the consumers of the iterator about the changes performed to the state machine due to this event. For example, units may have been deleted, added, changed position, etc.

let source: PathBuf = PathBuf::new();
let res = s2protocol::state::SC2EventIterator::new(&source)?;
for (event, change_hint) in res.into_iter() {
    println!("{},", serde_json::to_string(&event)?);
}

Balance Data

Units perform abilities that are specific to different patches. The SCII Editor allows the balance data to be exported. This includes:

• The abilities for each unit (in XML format)
• The ability Icons in DDS format
• The map in .tga format. So, a unit, say, for an Overlord, may run ability link "43", within this ability, a command indexed as "1", Inside the Overlord.xml there is:

<?xml version="1.0" encoding="utf-8"?>
<unit id="Overlord">
  <abilities>
    <ability id="move" index="43">
      <command id="Move" index="0">
        <! <meta icon, hotkey, range, etc -->
      </command>
      <command id="Patrol" index="1">
        <! <meta icon, hotkey, range, etc -->
      </command>
    </ability>
  </abilities>
</unit>

To use the exported balance data, data must be exported and stored in per-version directory with the following structure: <somepath>/94137/BalanceData/Overlord.xml where 94137 is the version of the exported XMLs.

To transform the --xml-data into an local-jsonified-version (stored in assets directory for now):

$ cargo run -r -- -v info --timing --source $HOME/SC2Replays/BalanceData/ --json-balance-data-dir $PWD/assets/BalanceData/ --output $PWD/assets/BalanceData/ balance-data-to-json
2025-08-30T18:18:04.528202Z  INFO s2protocol::game_events::ability::balance_data: Processed 1058 total units
2025-08-30T18:18:04.528218Z  INFO s2protocol::game_events::ability::balance_data::json_handler: Writing balance data to JSON files in /home/seb/git/s2protocol-rs/assets/BalanceData/

For example:

$ cargo run -- --source assets/FieldsDeath202507.SC2Replay --max-events 450 --color --json-balance-data-dir $PWD/assets/BalanceData/ --verbosity-level info get transist-events
     Running `target/debug/s2protocol --source assets/FieldsDeath202507.SC2Replay --max-events 450 --color --xml-balance-data-dir /home/seb/SC2Replays/BalanceData/ --verbosity-level warning get transist-events`
2025-08-30T18:19:47.983171Z  INFO s2protocol::game_events::ability::balance_data::json_handler: Reading balance data from JSON files in /home/seb/git/s2protocol-rs/assets/BalanceData/
2025-08-30T18:19:48.532272Z  INFO s2protocol::game_events::ability::balance_data::json_handler: Read 1058 versioned balance units from JSON files
2025-08-30T18:19:48.532290Z  INFO s2protocol::cli: Processing "assets/FieldsDeath202507.SC2Replay"
2025-08-30T18:19:48.532848Z  INFO s2protocol::cli: Transducing through both Game and Tracker Events
2025-08-30T18:19:48.576246Z  INFO s2protocol::state: Collected 1058 unit definitions for protocol version 94137 out of 1058 total definitions
...

If the XMLs/JSON for a specific version doesn't exist, all ability Strings will appear as "".

TODO:

• The json exports from BalanceData could be loaded from a remote repo (github maybe?), otherwise people need to have this repo cloned.
• The Balance Units contain strengths and weaknesses, we could return as part of ChangeHint a ratio of how good/bad the units are towards the existing enemy army.
• The ability-index/command-index may be compatible between multiple protocol versions.
• arrow-ipc tables can be created for BalanceUnits

Displaying the replay on the terminal

Suppose you wanted to debug/inspect a replay, you can draw the events to the terminal, for example:

$ cargo run --features syntax,dep_ratatui,tracing_off -- --max-loop 1000 --color --json-balance-data-dir $PWD/assets/BalanceData/ --source $PWD/assets/FieldsDeath202507.SC2Replay get transist-events

BREAKING CHANGES

v3

• Feature arrow has been renamed to dep_arrow as we now use the arrow crate.
• Previously the generated arrow IPC files relied on a sha256 of the file as "key", this wasted a lot of space and has been changed into a sequential As a result, queries must use the new ext_fs_id, which also means all the files must be generated in bulk and are no longer independent. The IPCs then is valid as a snapshot generated as a whole. v3.4
• There is only one iterator provided now, that goes through both the Tracker and Game events to build the game state. Previously two iterators were provided that build partial state only for either track/game and the result was inconsistent, plus lots of duplicated code.

Interacting with polars

TODO:

• The UpdateTargetPoint Cmd arrow snapshot should contain the unit name, otherwise kindof to have an ability withouth it.

Generating the IPC Arrow datasets

In the directory ipcs/ one .ipc file will be created per implemented data type. The --source is the directory that contains the replay directory (Or a single file). Multiple subdirectories are supported. Files are processed using parallel operations. For 17K replays (2.3 GBs) it takes 120 seconds to parse/transform/split them. YMMV, in this case only 10K files had valid init data (as in are supported protocol versions).

$ mkdir -p ipcs/
$ cargo run -r --no-default-features --features=dep_arrow,tracing_off -- -v error --timing --source $HOME/SCReplaysOnNVMe --json-balance-data-dir $PWD/assets/BalanceData/ --output $HOME/git/s2protocol-rs/ipcs/ write-arrow-ipc --process-max-files 1000000
36752 files have valid init data, processing...
Total time: 396.363965713s
$ du -sh ipcs
22G     ipcs
$ ls -ltra ipc
total 22239120
drwxr-xr-x  2 seb seb       4096 Aug 17 18:27 .
drwxr-xr-x 12 seb seb       4096 Aug 30 18:14 ..
-rw-r--r--  1 seb seb  117183106 Aug 30 20:45 lobby_init_data.ipc
-rw-r--r--  1 seb seb   10095306 Aug 30 20:45 details.ipc
-rw-r--r--  1 seb seb 2173322874 Aug 30 20:46 stats.ipc
-rw-r--r--  1 seb seb  179426002 Aug 30 20:47 upgrades.ipc
-rw-r--r--  1 seb seb 9958263882 Aug 30 20:48 unit_born.ipc
-rw-r--r--  1 seb seb 5859714578 Aug 30 20:49 unit_died.ipc
-rw-r--r--  1 seb seb 3479428050 Aug 30 20:50 cmd_target_point.ipc
-rw-r--r--  1 seb seb  995379658 Aug 30 20:51 cmd_target_unit.ipc

Jupyter Notebooks

The jupyter notebook with examples on how to interact with the data are available in s2-polars-data-analysis

polars-cli

$ cargo install polars-cli
$ echo "SELECT ext_fs_id, MAX(minerals_lost_army) FROM read_ipc('/home/seb/git/s2protocol-rs/ipcs/stats.ipc') GROUP BY ext_fs_id ORDER BY minerals_lost_army DESC;"|polars
┌───────────┬────────────────────┐
│ ext_fs_id ┆ minerals_lost_army │
│ ---       ┆ ---                │
│ u64       ┆ i32                │
╞═══════════╪════════════════════╡
│ 46076     ┆ 40078725           │
│ 50221     ┆ 26858850           │
│ 44624     ┆ 23460100           │
│ 25898     ┆ 14187775           │
│ 46088     ┆ 9492100            │
│ …         ┆ …                  │
│ 28169     ┆ 217075             │
│ 32336     ┆ 190500             │
│ 47505     ┆ 178256             │
│ 38654     ┆ 177675             │
│ 24162     ┆ 168120             │
└───────────┴────────────────────┘
& echo "SELECT ability, count() FROM read_ipc('/home/seb/git/s2protocol-rs/ipcs/cmd_target_unit.ipc') GROUP BY ability ORDER BY len DESC LIMIT 10"|polars
┌───────────────────────────────┬─────────┐
│ ability                       ┆ len     │
│ ---                           ┆ ---     │
│ str                           ┆ u32     │
╞═══════════════════════════════╪═════════╡
│                               ┆ 7457415 │
│ attack.Execute                ┆ 36377   │
│ Transfusion.Execute           ┆ 16004   │
│ SpawnLarva.Execute            ┆ 12291   │
│ ChronoBoostEnergyCost.Execute ┆ 10111   │
│ SCVHarvest.Gather             ┆ 9680    │
│ Build.Extractor               ┆ 4896    │
│ Build.Refinery                ┆ 3363    │
│ DroneHarvest.Gather           ┆ 2212    │
│ Build.Assimilator             ┆ 1754    │
└───────────────────────────────┴─────────┘

Status

• Replay Tracker, Game Events and Chat Message Events for protocol75689
• Replay Tracker, Game Events and Chat Message Events for protocol84643
• Replay Tracker, Game Events and Chat Message Events for protocol87702
• Replay Tracker, Game Events and Chat Message Events for protocol88500
• Replay Tracker, Game Events and Chat Message Events for protocol89634
• Replay Tracker, Game Events and Chat Message Events for protocol89720
• Replay Tracker, Game Events and Chat Message Events for protocol90136
• Replay Tracker, Game Events and Chat Message Events for protocol90779
• Replay Tracker, Game Events and Chat Message Events for protocol90870
• Parsing unit movement is done.
• Decoding the tag/recycle done to match Game Events.
• Game Events are parsed (tho some that seem irrelevant are skipped).
• Read the version and from the version call the correct module so that we can support multiple modules.
• Support for MPQ embedded file: replay.initData
• Add the remaining Tracker/Game event types.
• Support for MPQ embedded file: replay.gamemetadata.json
• Support for MPQ embedded file: replay.attributes.events

version compatibility.

After a bit of testing, it seems most of the types are compatible between versions, so only when they differ would they make part of the protocol version. Since I started this exercise on protocol87702, all types would be relative to it. That is, most modules would re-use protocol87702 as much as possible. This explains why old-er versions such as 75689 would still reference 87702 as much as possible.

The generator above thus would show example code S2ProtoResult created in favour of unwrapping/panic'ing.

Generating protocol-specific code:

The rust code for the protocols versions available were generated using: This would now be compared with ./src/versions/protocol99999.template file and from there we can analyze what has changed. Notably, the number of bits used for the Chat Message is still miscalculated to 3 so it needs to be dismissed.

mkdir src/versions/protocol89720/
RUST_LOG_SPAN_EVENTS=full RUST_LOG=debug cargo watch -i src/versions/protocol89720/mod.rs -x 'run -- --source ../s2protocol/json/protocol89720.json generate --output src/versions/protocol89720/mod.rs'
# Add the new module to src/versions/mod.rs
# Run rust format on the new src/versions/protocol87702/mod.rs file
# cargo check, cargo build, etc
# Additionally some code to transform from Protocol-Specific to Protocol-Agnostic was added, TODO: Add to generator.rs

JSON Spec Sources

Blizzard/s2protocol repo