emulator: Julius
type: standalone
core_classification: game_engine
source: "https://github.com/bvschaik/julius"
upstream: "https://github.com/bvschaik/julius"
profiled_date: "2026-10-17"
source_commit: "33c777019b2640b847b73815c3b4344cf7bd9576"
core_version: "1.7.0"
display_name: "Caesar III (Julius)"
cores:
  - "julius"
systems:
  - "caesar3"

notes: |
  Open-source reimplementation of Impressions Games' Caesar III engine.
  It reads every graphic, text, sound and scenario from an installed copy
  of the game; nothing is bundled.

  The data directory is the command-line argument. pre_init() makes it
  the base path and runs game_pre_init(); a missing directory shows
  "Julius requires the original files from Caesar 3" and exits
  (ref: src/platform/julius.c:488-501, 580-586). File lookups are
  case-corrected inside that directory.

  Startup loads, in order, the text and message files c3.eng and
  c3_mm.eng (c3.rus and c3_mm.rus as the alternative pair)
  (ref: src/game/game.c:48-63, src/core/lang.c:141-165), the central
  climate graphics c3.sg2 and c3.555, the barbarian enemy graphics
  goths.sg2 and goths.555, and c3_model.txt (ref: src/game/game.c:79-104).
  Any of them missing aborts init. The_empire.555 is loaded with the
  climate graphics; a wrong size is logged and the game continues
  (ref: src/core/image.c:283-293, 323). The other climates, enemies,
  sounds, videos and scenario maps are opened from the same directory on
  demand.

  Recalbox lists Caesar III under roms/ports/Caesar3 with c3.exe as the
  entry and patches config and save paths into /recalbox/share.

files:
  - name: "caesar3/"
    type: directory
    path: "caesar3/"
    system: "caesar3"
    category: game_data
    required: true
    description: "Caesar III install directory"
    source_ref: "src/platform/julius.c:488-501"
    note: "Given on the command line; every game file is opened by name inside it."
  - name: "c3.eng"
    path: "caesar3/c3.eng"
    system: "caesar3"
    category: game_data
    required: true
    description: "Caesar III interface text"
    source_ref: "src/core/lang.c:23, 74-80, 141-165"
    note: "Rejected when outside MIN_TEXT_SIZE..MAX_TEXT_SIZE. c3.rus replaces it on a Russian install."
  - name: "c3_mm.eng"
    path: "caesar3/c3_mm.eng"
    system: "caesar3"
    category: game_data
    required: true
    description: "Caesar III message text"
    source_ref: "src/core/lang.c:24, 129-150, 160-165"
    note: "Loaded as a pair with c3.eng; c3_mm.rus replaces it on a Russian install."
  - name: "c3.sg2"
    path: "caesar3/c3.sg2"
    system: "caesar3"
    category: game_data
    required: true
    description: "Main graphics index, central climate"
    source_ref: "src/core/image.c:48-52, 295-306, src/game/game.c:83-86"
  - name: "c3.555"
    path: "caesar3/c3.555"
    system: "caesar3"
    category: game_data
    required: true
    description: "Main graphics bitmaps, central climate"
    source_ref: "src/core/image.c:53-57, 314-317, src/game/game.c:83-86"
  - name: "goths.sg2"
    path: "caesar3/goths.sg2"
    system: "caesar3"
    category: game_data
    required: true
    description: "Barbarian enemy graphics index"
    source_ref: "src/core/image.c:79, 667-675, src/game/game.c:87-90"
  - name: "goths.555"
    path: "caesar3/goths.555"
    system: "caesar3"
    category: game_data
    required: true
    description: "Barbarian enemy graphics bitmaps"
    source_ref: "src/core/image.c:101, 681-684, src/game/game.c:87-90"
  - name: "c3_model.txt"
    path: "caesar3/c3_model.txt"
    system: "caesar3"
    category: game_data
    required: true
    description: "Building cost and desirability model"
    source_ref: "src/building/model.c:83-88, src/game/game.c:101-104"
  - name: "The_empire.555"
    path: "caesar3/The_empire.555"
    system: "caesar3"
    category: game_data
    required: false
    description: "Empire map bitmap"
    source_ref: "src/core/image.c:68, 283-293"
    note: "A short read is logged and the empire map stays blank."