From-scratch reimplementation of the Sword of the Stars (2006) engine. Clean-room; engine code only — bring your own game copy. Planning/RE evidence live in sots-re.
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The tail's phase 34 sweeps every player over every ship of every fleet and
records the design of each ship it can see. Three of the recorder's rules are
invisible from a save and every one of them changes the answer:
* the lookup key is the DESIGN ID ALONE, not the (design, owner) pair;
* a re-observation ERASES the record and PUSHES A COPY ON THE BACK rather than
updating in place, so the list ends in last-observation order and the record's
first-seen turn survives the move. This is why a turn's output is a
PERMUTATION of its input and not an append -- which is what made the group
look like 55 unrelated leaves;
* the list is CAPPED AT 20 RECORDS PER DESIGN OWNER, counted from the most
recent end, and the cap is applied after EVERY record call rather than once
per sweep. On an empire with more than twenty designs in service that thrashes
inside the one sweep: records are evicted and re-created, and a re-created
record's first-seen turn is reset.
A fourth rule is a guard on the DESIGN'S OWNER and not on the observer: a design
owned by an NPC that is not a rebel AI is never observed by anyone. Every
observation record in every corpus save agrees -- the NPC factions' 26 designs
appear in nobody's list -- and removing the guard costs 9 leaves on the canonical
pair while costing nothing on the rich turn, so the two pairs test different rules
and both were run.
TWO THINGS ARE NOT MODELLED AND BOTH ARE NAMED IN THE CATALOG TEXT. The gate is a
two-bit-per-player word on the ship that is NOT serialised; this phase stands it
in with ownership, which is the smallest rule correct on every state the corpus
holds, because on both reference pairs no player observes another player's ship.
That is a hypothesis with a cheap falsifier and it is labelled as one. And the
phase's tech and weapon arms are not implemented: the original feeds the design
through three set builders into the observed-tech and observed-weapon lists, and
those builders are not decoded.
Measured, closed and regressed never netted:
canonical pair turn2 -> turn3 62 -> 61 leaves 1 closed / 0 regressed
rich turn ad-turn27 -> pinB 1092 -> 1058 36 closed / 2 regressed
The 2 are two `otnF` words at positions whose `odid` also moves, i.e. positions
that now hold a different record; and the 21 design leaves that remain are the
shadow of ship construction, not of this phase -- two designs receive their first
ships during that turn and no phase here builds a ship. Fed the true post-turn
ship list, the same code leaves 1 leaf of 55.
Host build 255/255; host ctest 57/59 with the two pre-existing corpus-writer
failures unchanged (12 of 43 saves, the SpecialProjectNameGen `usp` item, not
this lane's); shim cross-build green; clean-room and shim-config checks green.
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| cmake | ||
| docs | ||
| include/generated | ||
| src | ||
| tests | ||
| third_party | ||
| tools | ||
| .gitignore | ||
| CMakeLists.txt | ||
| CMakePresets.json | ||
| CONTRIBUTING.md | ||
| LICENSE | ||
| README.md | ||
sots-engine
A from-scratch, functional reimplementation of the engine behind Sword of the Stars (2006). Not a byte-for-byte decompilation: behavior-equivalent code, built up one verified piece at a time (OpenRCT2-style) until the tree can build the whole application on its own.
Bring your own game. This repository contains engine code only. Game data, assets, saves, and
the original binaries are never included; tests and tools read an owner-supplied copy via
$SOTS_DATA_DIR. See CONTRIBUTING.md for the clean-room rules.
Status
Phase 2. M0 done — the shim frontend (src/shim/, a proxy binkw32.dll the original game
loads) builds, deploys, hooks, and logs from a real game launch. Engine code accrues under
src/mars/ and src/game/; each module is oracle-verified against the owner's game data before merge:
mars/parse— brace-block +.effectreaders (1,531/1,531 files agree with the reference)mars/text— flat key/value tables, id manifests, CSV (64/64 files agree)game/sim— strategic formulas (economy, research, colonies, movement) as pure functions; 356 hand-computed checksmars/vfs—.gob(ZIP) archive reader + loose-file override; entry counts and bytes verified againstunzipmars/stream— the game's self-describing save/serialization format (reader, writer, typed shapes) + gzip; three real saves round-trip byte-identicalmars/rng— MT19937 with save-state load/store; layout confirmed against real saves, draw mappings read off the binary (docs/mars-rng.md)game/data— typed catalogs (weapons, ship sections, turrets, id registries, tech tree, strings) with cross-reference checks; 229k values agree with the referencegame/design— ship-design assembly/fit/tech-gating rules and derived stats; validates all 127 stock designs from real savesapp— the standalone:sots_turnloads a save, runs one strategic turn over the published phase order of all three turn drivers, and writes a save. 14 of the 44 turn-driver phases are modelled; every phase that is not appears in the run log as a named no-op. How far it is from the byte-match, and what stands in the way, is indocs/S-standalone.md
Build: cmake --preset host && cmake --build --preset host && ctest --preset host (Linux);
tools/sync-build.sh cross-builds the shim on the lab box and stages it for deployment.
Layout (grows with the work)
src/shim/— binkw32 proxy + hooks + old-vs-new compare harness (frontend #1)src/mars/,src/game/— the engine and game reimplementation (accruing)src/app/— the standalone turn driver (frontend #2): load a save, run a turn, write a saveinclude/generated/sots_addresses.h— binary facts (RVAs/prototypes), generated from the RE repotests/— host tests; real-data tests skip unless$SOTS_DATA_DIRis settools/— build (MinGW i686 cross) and deploy scripts
Planning, findings, and verification evidence are tracked in the private RE repo (sots-re).