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, and 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."