Dungeon Master II: Skullkeep Technical Reference

Status reviewed 2026-09-12. DM2 has bounded source-owned routes from DOS, Amiga, FM Towns and Macintosh real media. Full campaign parity, native non-DOS saves and some combat/UI owners remain active work.

Scope

DM2 V1 follows skproject, DMWeb format notes and the retained disassembly evidence. It is independent from the DM1/CSB compatibility path. Each edition requires its own authenticated data pair. The Japanese FM Towns edition retains its own disc as its only data owner: a GDAT-keyed localisation bridge supplies canonical text for the selected language and never requires a PC-English GRAPHICS.DAT companion.

Verified real-media launch matrix

The following checks use the supplied original ZIPs directly in bounded memory. They do not extract a game installation, invoke an emulator, or replace unavailable source material with generated art. They establish native boot/menu/new-game and the listed bounded runtime path; they are not a claim of complete visual or gameplay parity.

Focused real-media cases cover the stated boundaries. A passing startup or runtime slice is not a visual-parity claim: title palette/timing, menu handoff, HUD, viewport, mouse/touch input, audio and dungeon composition each need their own edition-owned evidence. Macintosh DM2 demo support is intentionally absent; it is not a fallback for any of the routes above.

Boot and GDAT

An incomplete profile remains at the launcher and does not clear the viewport or paint generated floor/ceiling art. The boot receipt records source identity, typed GDAT sections, title/menu, HUD, dungeon, and no-fallback readiness.

The GDAT pipeline exposes dtPalIRGB, dtPalette16, dt07 interface/title records, Rect14 placement, map GRAPHICSSET values, and map-chip assets. The viewport resolves raw GDAT addresses before decode. Missing mandatory material is a no-draw receipt, never a substitute. Wall cache keys include graphics style to prevent material leakage between maps.

Runtime

M10 owns party, door, item, creature, projectile, actuator, and dungeon state. The viewport consumes typed plans. Outdoor routes pass the active source sky, ground, and weather state; indoor routes are clear. Rain, mist, and thunder do not create procedural pixels without a verified original overlay asset.

Feature queue status (Q-DM2-01 through Q-DM2-10)

The ten DM2 feature lanes have focused coverage:

The work continues as continuous lanes (Lane A through E) rather than discrete queue items. Active lanes:

• Lane A — SkWinCore symbol audit. Closes MISSING rows in docs/reference/audits/SKPROJECT_DM2_NAMED_SYMBOL_AUDIT.tsv in small batches, source-locking each skproject/SKULLWIN symbol against SKWIN/SkWinCore.cpp and SkGlobal.cpp before implementation. The current disposition is the TSV itself; do not copy a historical row count into a status summary.
• Lane B — Audible playback backend. dm2_v1_sound_bind_gdat_loader() wires DM2_PLAY_MUSIC, DM2_PLAY_SOUND, and DM2_QUERY_SND_ENTRY_INDEX to real GDAT sound data with an SDL3 mixing backend (6000 Hz U8 mono stream, additive sdlAudMix-shaped mixing). M11 binds the described backend immediately after an authenticated DM2 boot handoff, before a resume or new-game route can publish live runtime state; failed boot does not bind it. See DM2 GDAT Internals for the PCM decode and voice-allocation detail. The remaining work is broader source-capture comparison and platform-specific audible behavior, not the M11 binding itself.
• Lane C — Real-data startup/dungeon gate repair. Fixed the DM2 real-data gate tests (2 failing as of v3.0.181, was 13) by refining the g1_w0_chains_disabled flag: real PC G1 DUNGEON.DAT disables w0 chain traversal (proven game data, not next-links), while synthetic skproject test fixtures preserve w0 chain traversal so existing fixture-based tests keep working. record_graph_complete is now enabled for skproject-loaded fixtures, unblocking wall-gfx/actuator/3D93B chain traversal in those fixtures.
• Lane D — Creature/cloud real-data passes. Source-locked the _4976_5aa4 occupancy grid and DRAW_FLYING_ITEM selection rules against SKWIN/SkWinCore.cpp (QUERY_CREATURE_5x5_POS, DRAW_STATIC_OBJECT’s occupancy walk, DRAW_FLYING_ITEM) and SkGlobal.cpp tables. See DM2 GDAT Internals for the creature V5 animation chain and occupancy-grid detail.
• Lane E — Real-data combat and drops mechanics. New dm2_v1_drops_resolve_gdat_creature_drops() reads the eleven-entry per-creature drop table from real GDAT data and resolves proven drop words with RNG-gated selection, matching SkWinCore.cpp’s creature-death drop route. Covers the defense route and combat-drop resolution path. The verified CREATURES→v1d296c AIDefinition defense byte is retained in the combat receipt, while the complete champion/hand/CMDSTR/RNG damage owner remains fail-closed. Tested by test_dm2_v1_drops_gdat_real_data (skip-safe against real data).

DOS SKSAVE1 WIELD boundary

The supplied original PC-DOS archive contains the real data/sksave0 through data/sksave3 .dat/.bak slots. Firestaff reads those members directly from the ZIP; it does not unpack or rewrite them. The source-owned SKSAVE1.DAT resume regression commits the original save and reaches one real WIELD calculation with these recorded inputs:

item=0x140c  creature=0x1116  power=26
dexterity=21 strength=48 skill=4
defense=170 armor=175 map difficulty=8 party power=11
result=miss, raw damage=0, final damage=0, applied HP damage=0

This is a useful ownership proof: the command, item, creature, stats and GDAT defense values are all read from the admitted original session. It is not a proof of a kill or a creature drop. The supplied route is a miss, and there is no matching original command/RNG trace for a hit; Firestaff therefore does not turn a generated command search into a retail death/drop claim. The post-death deallocation and drop path remains closed until an authentic input-to-CD/RAM trace supplies that missing evidence.

Source reference for all DM2 work: skproject (SKULLWIN/SkWinCore.cpp, SkGlobal.cpp, plus the per-file c_*.cpp modules named in the symbol audit).

Verification

cmake --build build --target test_dm2_v1_boot_profile_smoke \
  test_dm2_v1_runtime_handoff_smoke test_dm2_v1_weather_no_synthetic_overlay \
  --parallel
./build/test_dm2_v1_boot_profile_smoke
./build/test_dm2_v1_runtime_handoff_smoke
./build/test_dm2_v1_weather_no_synthetic_overlay

Real-data gate and lane-specific tests:

cmake --build build --target test_dm2_v1_drops_gdat_real_data \
  test_dm2_v1_creature_occupancy_flying_item test_dm2_v1_sound_gdat_real_data \
  --parallel
./build/test_dm2_v1_drops_gdat_real_data
./build/test_dm2_v1_creature_occupancy_flying_item
./build/test_dm2_v1_sound_gdat_real_data

For the GDAT record chain, interface tables, and host receipts, see DM2 GDAT Internals.