Open Scrantic: rebuilding the Johnny Castaway screensaver engine in Rust

The question

How can a 16-bit screensaver’s script interpreter, story schedule and random behavior run on modern systems?

What REA did

The developer explicitly credits Claude Code with REA for disassembling and decompiling SCRANTIC.SCR, recovering resource formats and script semantics, and producing the Rust implementation and documentation.

Author-reported results

The public Rust engine implements resource loading, TTM/ADS script execution, story progression, timing and the original random-number generator. ENGINE.md records recovered rules and deliberate differences; the author supplies Windows, macOS and Linux release paths.

Limitations and unverified claims

The engine requires the user’s own matching original files and rejects other executable builds. Full-frame redraw, optional image/audio processing and settings differ from the original. Cross-platform behavior and equivalence were not independently tested here; raw REA sessions were not found in the reviewed files.

What to learn

Keep original asset ownership separate from engine code, preserve arithmetic and scheduling rules, and document deliberate compatibility differences.

REA usage evidence in the source

Together they were used to disassemble and decompile the original `SCRANTIC.SCR`, recover the resource formats and script semantics, and write the Rust code, tests and documentation.

Excerpt formatting is simplified. Read the original source for full context.

Original sources

• Primary source / pinned evidence
• Project / demo
• Additional source 1
• Additional source 2
• Additional source 3

Independent editorial summary. Credit belongs to the original authors. Target software, installers and complete decompiler output are not redistributed here.