diff --git a/CMakeLists.txt b/CMakeLists.txt
index 60b59ca..7249c71 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,6 +21,7 @@ target_include_directories(sots_addresses INTERFACE ${CMAKE_SOURCE_DIR}/include)
 add_subdirectory(src/mars/parse)   # brace-block + .effect readers   (lib mars_parse)
 add_subdirectory(src/mars/text)    # flat-kv, id-manifest, csv       (lib mars_text)
 add_subdirectory(src/game/sim)     # strategic formulas, pure          (lib sots_game_sim)
+add_subdirectory(src/mars/vfs)     # .gob ZIP reader + native override (lib mars_vfs, miniz)
 
 if(WIN32)
   # ---- shim: proxy binkw32.dll that the original game loads (Phase 2 frontend) ----
@@ -44,7 +45,7 @@ else()
   add_executable(addr_smoke tests/addr_smoke.cpp)
   target_link_libraries(addr_smoke PRIVATE sots_addresses)
   add_test(NAME addr_smoke COMMAND addr_smoke)
-  foreach(_t mars_parse mars_text game_sim)
+  foreach(_t mars_parse mars_text game_sim mars_vfs)
     if(EXISTS ${CMAKE_SOURCE_DIR}/tests/${_t}/CMakeLists.txt)
       add_subdirectory(tests/${_t})
     endif()
diff --git a/README.md b/README.md
index 6bb0263..ae79692 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,7 @@ loads) builds, deploys, hooks, and logs from a real game launch. Engine code acc
 - `mars/parse` — brace-block + `.effect` readers (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 checks
+- `mars/vfs` — `.gob` (ZIP) archive reader + loose-file override; entry counts and bytes verified against `unzip`
 
 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.