Deadgame2 - sekai2026

Description

The provided archive was misc_deadgame2.tar.gz, containing misc_deadgame2/DeadGame2.SC2Replay. The replay is a StarCraft II MPQ archive. Metadata identified map title Tunguska, GameVersion 5.0.15.96999, and Base96999.

The goal was to recover the complete SeKaiCTF{...} flag from replay data. The visible chat gave most of the flag, while a hint about positions pointed to hidden text encoded in tracker coordinates.

Tools

• python3.11
• mpyq for extracting the MPQ replay archive
• s2protocol for decoding StarCraft II replay streams
• Pillow for rendering coordinate plots

The local environment used vendor311 packages because the bundled s2protocol code was compatible with Python 3.11.

Extraction and Parsing

After unpacking the challenge archive, treat DeadGame2.SC2Replay as an MPQ archive and extract the replay streams. The important files were:

• replay.message.events - in-game chat messages
• replay.tracker.events - unit and positional tracker events

The message stream can be decoded directly with the matching/latest bundled s2protocol protocol module:

#!/usr/bin/env python3
from pathlib import Path
from s2protocol.versions import protocol97364 as protocol

data = Path("extract/replay.message.events").read_bytes()

for event in protocol.decode_replay_message_events(data):
    if event.get("_event") != "NNet.Game.SChatMessage":
        continue
    text = event["m_string"].decode("utf-8", "replace")
    if text:
        print(event["_gameloop"], event["_userid"]["m_userId"], text)

Chat Fragment Recovery

The decoded chat stream contained direct flag fragments plus the key hint:

...