emulator: ioRTCW
type: standalone
core_classification: community_fork
source: "https://github.com/iortcw/iortcw"
upstream: "https://github.com/iortcw/iortcw"
profiled_date: "2026-10-04"
source_commit: "438e7d413b5f7277187c35b032eb0ef9093ae778"
display_name: "ioRTCW"
cores: []
systems: [return-to-castle-wolfenstein]

notes: |
  Return to Castle Wolfenstein source port derived from the ioquake3
  codebase and the id Software GPL release of RTCW. Ships as two
  separate executables: Single-player and Multiplayer, each with its
  own filesystem layer under SP/code/ and MP/code/.

  BASEGAME is "main" for both builds.
  ref: SP/code/qcommon/qcommon.h:628, MP/code/qcommon/q_shared.h:62

  Both builds stop with a fatal error when main/pak0.pk3 is missing, or
  present with a checksum other than 1886207346. A demo pak0 under
  demomain/ is accepted with a warning and skips the point-release
  check.
  ref: SP/code/qcommon/files.c:3842-3972, MP/code/qcommon/files.c:3836-3966

  Single-player (SP/code/qcommon/files.c) then requires the four
  point-release paks; a missing one is fatal, a wrong checksum only
  prints a warning:
    main/sp_pak1.pk3  five localized checksums (en/fr/gm/it/sp)
    main/sp_pak2.pk3  3033901371, or 285968110 for the German release
    main/sp_pak3.pk3  five localized checksums
    main/sp_pak4.pk3  GOTY edition pak, 4131017020 for every language
  ref: SP/code/qcommon/files.c:187-225 (checksum arrays),
       SP/code/qcommon/qcommon.h:637-638 (NUM_ID_PAKS 6, NUM_SP_PAKS 4),
       SP/code/qcommon/files.c:3720-3827 (FS_CheckSPPaks)

  Multiplayer (MP/code/qcommon/files.c) requires the six mp_pak files
  the same way:
    main/mp_pak0.pk3  checksum 764840216
    main/mp_pak1.pk3  checksum -1023558518
    main/mp_pak2.pk3  checksum 125907563
    main/mp_pak3.pk3  checksum 131270674
    main/mp_pak4.pk3  checksum -137448799
    main/mp_pak5.pk3  checksum 2149774797
    main/mp_bin.pk3   or mp_bin0.pk3 (1.51c) - VM/binary pak, optional
  ref: MP/code/qcommon/files.c:198-218 (mppak_checksums, binpak_checksums),
       MP/code/qcommon/files.c:3721-3821 (FS_CheckMPPaks)

files:
  # ================================================================
  # main/ - shared base
  # ================================================================

  - name: "pak0.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/pak0.pk3"
    required: true
    source_ref: "SP/code/qcommon/files.c:183-185, 3865-3882, 3950-3967, MP/code/qcommon/files.c:194-196, 3859-3876, 3944-3961"
    note: "RTCW retail base. Checksum 1886207346 in both builds; fatal when missing or when the checksum differs."
    unsourceable: "retail data the collection does not hold; a same-named file of another game must not stand in"

  # ================================================================
  # main/ - single-player point-release paks
  # ================================================================

  - name: "sp_pak1.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/sp_pak1.pk3"
    required: true
    source_ref: "SP/code/qcommon/files.c:188, 196, 204, 212, 220, 3735-3767, 3806-3826"
    note: "Single-player build: fatal when missing. One checksum per language (en/fr/gm/it/sp); a mismatch prints a warning."

  - name: "sp_pak2.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/sp_pak2.pk3"
    required: true
    source_ref: "SP/code/qcommon/files.c:189, 197, 205, 213, 221, 3806-3826"
    note: "Single-player build: fatal when missing."

  - name: "sp_pak3.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/sp_pak3.pk3"
    required: true
    source_ref: "SP/code/qcommon/files.c:190, 198, 206, 214, 222, 3806-3826"
    note: "Single-player build: fatal when missing."

  - name: "sp_pak4.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/sp_pak4.pk3"
    required: true
    source_ref: "SP/code/qcommon/files.c:191-192, 199-200, 207-208, 215-216, 223-224, 3806-3826"
    note: "Single-player build: fatal when missing. GOTY edition pak, one checksum (4131017020) for every language."

  # ================================================================
  # main/ - multiplayer paks
  # ================================================================

  - name: "mp_pak0.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/mp_pak0.pk3"
    required: true
    source_ref: "MP/code/qcommon/files.c:199, 3736-3751, 3800-3820"
    note: "Multiplayer build: fatal when missing. A checksum mismatch prints a warning."

  - name: "mp_pak1.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/mp_pak1.pk3"
    required: true
    source_ref: "MP/code/qcommon/files.c:200, 3800-3820"
    note: "Multiplayer build: fatal when missing."

  - name: "mp_pak2.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/mp_pak2.pk3"
    required: true
    source_ref: "MP/code/qcommon/files.c:201, 3800-3820"
    note: "Multiplayer build: fatal when missing."

  - name: "mp_pak3.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/mp_pak3.pk3"
    required: true
    source_ref: "MP/code/qcommon/files.c:202, 3800-3820"
    note: "Multiplayer build: fatal when missing."

  - name: "mp_pak4.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/mp_pak4.pk3"
    required: true
    source_ref: "MP/code/qcommon/files.c:203, 3800-3820"
    note: "Multiplayer build: fatal when missing."

  - name: "mp_pak5.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/mp_pak5.pk3"
    required: true
    source_ref: "MP/code/qcommon/files.c:204, 3800-3820"
    note: "Multiplayer build: fatal when missing."

  - name: "mp_bin.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/mp_bin.pk3"
    required: false
    source_ref: "MP/code/qcommon/files.c:209, 1596-1613"
    note: "VM/binary pak, 1.4/1.41. The client extracts game dlls only from paks whose checksum is listed."

  - name: "mp_bin0.pk3"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "main/mp_bin0.pk3"
    required: false
    source_ref: "MP/code/qcommon/files.c:210, 1596-1613"
    note: "VM/binary pak, 1.51c variant."

  # ================================================================
  # demomain/ - demo paks, one per build
  # ================================================================

  - name: "pak0.pk3"
    description: "Single-player demo"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "demomain/pak0.pk3"
    required: false
    source_ref: "SP/code/qcommon/files.c:181, 3858-3863, 3933-3946, 3969-3970"
    note: "Single-player build: a pak0 under demomain/ with checksum 2985661941 stands in for main/pak0.pk3 with a warning, and the point-release check is skipped."
    unsourceable: "demo data the collection does not hold yet; a same-named file of another game must not stand in"

  - name: "pak0.pk3"
    description: "Multiplayer demo"
    category: game_data
    system: return-to-castle-wolfenstein
    path: "demomain/pak0.pk3"
    required: false
    source_ref: "MP/code/qcommon/files.c:192, 3852-3857, 3927-3940, 3963-3964"
    note: "Multiplayer build: a pak0 under demomain/ with checksum 2031778175 stands in for main/pak0.pk3 with a warning, and the point-release check is skipped."
    unsourceable: "demo data the collection does not hold yet; a same-named file of another game must not stand in"