Case study

Open Sosaria: reconstructing the 1981 Apple II Ultima engine

Open Sosaria reimplements the 1981 Apple II Ultima engine in C99 for modern PCs. It parses the player's DOS 3.3 disk images, reconstructs game systems from observed behavior, and synthesizes some audio from disassembled 6502 timing loops; the author reports that the game can be completed.

Targets: Game
Category: Independent reconstruction cases
Relationship: Independent reconstruction project
Sources reviewed: 2026-11-06
Evidence class: C2 code & docs, no demo or download

Stars: 14
Last commit: 2026-08-22
Language: C
License (GitHub): MIT

GitHub data as of 2026-11-10

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Evidence

Observed: Code, documentation and a download method observed; no demo found.
Checked: 2026-11-09

How evidence classes are assigned

Requirements & limits

Prerequisites: Players must provide their own Apple II game disk images.
Prerequisites: Building requires a C99 compiler, GLFW3, OpenGL, and GNU Make.
Limits: The author reports an end-to-end beatable game and ongoing refinement of logic and rendering.
License: MIT License.

Cite

BibTeX

@misc{open-sosaria-ultima-case,
  title = {{Open Sosaria: reconstructing the 1981 Apple II Ultima engine}},
  howpublished = {\url{https://github.com/delcodigo/open-sosaria}},
  url = {https://github.com/delcodigo/open-sosaria},
  urldate = {2026-11-06},
  note = {Awesome REA entry: \url{https://awesomerea.org/resources/open-sosaria-ultima-case/}}
}

Plain text

Open Sosaria: reconstructing the 1981 Apple II Ultima engine. https://github.com/delcodigo/open-sosaria (accessed 2026-11-06). Awesome REA entry: https://awesomerea.org/resources/open-sosaria-ultima-case/

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About this entry

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Primary sources

README.md GitHub · delcodigo/open-sosaria · Revision 578828d
docs/engine-reinterpretation-notes.md GitHub · delcodigo/open-sosaria · Revision 578828d