Analysis and reimplementation of Railroad Tycoon 3

The old executable is at ./rt3_wineprefix/drive_c/rt3/RT3.exe

Our first task is to understand the executable's high-level control loops and subsystem boundaries well enough to choose good rewrite targets. As we go, we document evidence, keep a curated function map, and stand up Rust tooling that can validate artifacts and later host replacement code.

The long-term direction is still a DLL we can inject into the original executable, patching in individual functions as we build them out. The active implementation milestone is now a headless runtime rehost layer that can execute deterministic world work, compare normalized state, and grow subsystem breadth without depending on the shell or presentation path. The current packed-event frontier is broader real grouped-descriptor coverage on top of the existing save-slice, snapshot, overlay-import, compact-control, and symbolic company-target workflows. The runtime already carries selected-company and controller-role context through overlay imports, and real descriptors 2 Company Cash, 13 Deactivate Company, and 16 Company Track Pieces Buildable now parse and execute through the ordinary runtime path, and descriptors 1 Player Cash and 14 Deactivate Player now join that batch through the same service engine. Synthetic packed records still exercise the same runtime without a parallel packed executor. The first grounded condition-side unlock now exists for negative-sentinel raw_condition_id = -1 company scopes, and the first ordinary nonnegative condition batch now executes too: numeric-threshold company finance, company track, aggregate territory track, and company-territory track rows can import through overlay-backed runtime context. Exact named-territory binding now executes, and the runtime now also carries the minimal event-owned train roster and opaque economic-status lane needed for real descriptors 8 Economic Status, 9 Confiscate All, and 15 Retire Train to execute through the same path. Descriptor 3 Territory - Allow All now executes too, reinterpreted as company-to-territory access rights rather than a territory-owned policy bit. Whole-game ordinary-condition execution now exists too: special-condition thresholds, candidate-availability thresholds, and economic-status-code thresholds now gate imported runtime records through the same service path, and that world-side condition batch now decodes from checked-in metadata instead of fixture-only ids: real special-condition label ids, real economic-status ids, and the recovered %1 Avail. candidate template plus candidate-name side strings all lower into the runtime condition model. Checked-in whole-game descriptor metadata now drives the first real world-side effect batch too: special-condition and candidate-availability setters import natively, and descriptor 110 Disable Stock Buying and Selling now lowers into the keyed runtime flag world.disable_stock_buying_and_selling. The recovered whole-game toggle batch is broader now too: descriptors 111..138, excluding the scalar Limited Track Building Amount slot, also lower into keyed world_flags for finance/trading, construction, and governance restrictions. Explicit the late recovered special-condition toggles now execute too where current evidence is equally strong: Use Bio-Accelerator Cars, Disable Cargo Economy, Disable Train Crashes, Disable Train Crashes AND Breakdowns, and AI Ignore Territories At Startup. Whole-game condition decode is broader now too: checked-in world-flag condition ids can lower into world_flag_equals gates for boolean equality/inequality forms, so real packed records can gate whole-game effects on existing world_flags without fixture-authored placeholder ids. Explicit unmapped world-condition and world-descriptor frontier buckets still remain where current checked-in metadata stops. Shell purchase-flow and selected-profile parity remain out of scope. Mixed supported/unsupported real rows still stay parity-only. The PE32 hook remains useful as capture and integration tooling, but it is no longer the main execution milestone.

Project Docs

Bootstrap design and workflow documents live in docs/.

• docs/README.md: handbook index and target hashes
• docs/control-loop-atlas.md: compatibility index for the split atlas
• docs/control-loop-atlas/: canonical atlas section files
• docs/setup-workstation.md: toolchain baseline and local setup
• docs/re-workflow.md: repeatable reverse-engineering workflow
• docs/function-map.md: canonical function-map schema and conventions

The first committed exports for the canonical 1.06 executable live in artifacts/exports/rt3-1.06/.

Rust Workspace

The Rust workspace is split into focused crates:

• rrt-model: shared types for addresses, function-map rows, and control-loop concepts
• rrt-runtime: headless runtime state, stepping, normalized event service, and persistence-facing runtime types
• rrt-fixtures: fixture schemas, loading, normalization, and diff helpers for rehost validation
• rrt-cli: validation, runtime fixture execution, state-diff tools, and repo-health checks
• rrt-hook: minimal Windows DLL scaffold for low-risk in-process loading, capture, and later integration experiments under Wine

For the current headless runtime smoke path, use cargo run -p rrt-cli -- runtime summarize-fixture fixtures/runtime/minimal-world-step-smoke.json or one of the broader runtime fixtures under fixtures/runtime/.

For the current hook smoke test, run tools/run_hook_smoke_test.sh. It builds the PE32 proxy, copies it into the local RT3 install, launches the game briefly under Wine with WINEDLLOVERRIDES=dinput8=n,b, and expects rrt_hook_attach.log to appear.