Multiplayer investigation

• All Halo world packages are under Levels/Halo1/Solo; there is no Multi branch.
• Eleven apparent CTF or KOTH map hits were random World Partition cell IDs.
• No Blood Gulch, Beaver Creek, Sidewinder, or other classic CE map name is indexed.
• The 27 companion pak files contain 200,029 entries, primarily Wwise audio and resources, with no map or asset package entries.
• The IoStore containers are indexed, Oodle-compressed UE5.5 containers and are not encrypted.

Live runtime result

The exposed variant classes are BlamGameEngineBaseVariant and BlamGameEngineCampaignVariant. The previously suspected BlamGameEngineVariant path is not an exposed runtime class. Reflected APIs include social options, campaign flags, per-player traits, team ally/enemy/friendly/traitor tests, Blam player-index resolution, network co-op detection, session readiness, replicated session-running state, and endpoint IDs.

Fourteen high-level session, lobby, and travel hooks registered but produced no callbacks during the captured interval. This is an observation, not proof that the official flow bypasses them: tracing may have begun after an earlier transition. The next probe snapshots reflected variant and network-component state and traces endpoint assignment directly.

Update 2026-10-21: superseded by the route that shipped: joins that go through the game's own join handler, as an accepted invite does (MJOLNIRLobby), converted maps with their own worlds and structure BSPs, and a patched constant in the simulation's load-map handler that starts the Megalo engine (see HaloSimulation_tag_release.dll). The plan is kept as written.

1. 1. Reuse co-op transport. Host and join through the supported campaign session flow so PlayFab, Party, identity, and replication already work. Compare a real two-human capture against the recorded solo baseline.
2. 2. Travel to a known campaign world. Test plain travel first, then the same path with a listen-server option. A15 is the smallest initial target: /Game/Levels/Halo1/Solo/A15/A15.
3. 3. Activate a game variant. Discover the live base and campaign variant objects, then trace the shell startup structures that choose campaign versus CTF.
4. 4. Supply map metadata. Campaign maps do not necessarily contain team spawns, flag stands, boundaries, or objective markers. Spawn these at runtime before treating the mode as playable.

Custom-map path

A custom map is a second-stage problem. The game can index unencrypted UE5.5 IoStore containers, and Retoc can produce pak, utoc, and ucas output. The unresolved constraint is cooking a compatible UE5.5 world with the game's custom versions, script imports, and required Blam components. A tiny travel-only test world should precede a full CTF arena.

Update 2026-10-21: solved. mjolnir level bake --standalone, with --world and --bsp, registers a map with a cooked world package of its own and its own structure BSPs, and MJOLNIRLevelLoader's native half resolves that world by name at load (native/map_registry). The converted classic maps ship this way (tools/level/convert_ce_map.sh).

MJOLNIRMultiplayer now uses the verified CU2 root-world paths and dispatches plain or listen-server travel through the live player controller. It still does not create or advertise a session, and travel has not yet been verified in HCE.

Update 2026-10-21: superseded. MJOLNIRLobby hosts games on the game's own co-op fireteam and advertises them: a host can set a game to PUBLIC GAME, which lists it on the hub, and FIND GAMES joins it the way an accepted invite does (PR #127, mods-v0.11.0). A match's game type reaches every fireteam client through the host's travel into the map. MJOLNIRMultiplayer keeps the travel commands below, plus mjolnir_mission, mjolnir_debug_ui and mjolnir_kick; the scan, trace and dump commands are MJOLNIRDiscovery's.

mjolnir_maps
mjolnir_travel a15
mjolnir_listen a15
mjolnir_scan_blam
mjolnir_scan_worlds
mjolnir_trace_network
mjolnir_dump_state