diff --git a/.github/workflows/clang-tidy.yaml b/.github/workflows/clang-tidy.yaml
index fa12e77512..03e8092c47 100644
--- a/.github/workflows/clang-tidy.yaml
+++ b/.github/workflows/clang-tidy.yaml
@@ -4,49 +4,17 @@ on: [pull_request]
 jobs:
   build:
     name: clang-tidy
-    strategy:
-      matrix:
-        os: [ubuntu-latest]
-        compiler: [gcc]
-        build_type: [Debug]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     steps:
-      - name: Set base_dir
-        run: echo "base_dir=$(pwd)" >> $GITHUB_ENV
-
       - uses: actions/checkout@v2
         with:
           fetch-depth: 0
-      - name: Install GCC
-        if: ${{ matrix.compiler == 'gcc' }}
-        run: |
-          sudo apt-get install g++
-      - name: Install dependencies
-        run: |
-          sudo apt-get update
-          sudo apt-get install \
-            cmake \
-            ninja-build \
-            python3 \
-            gettext \
-            qtbase5-dev \
-            libqt5svg5-dev \
-            libkf5archive-dev \
-            liblua5.3-dev \
-            libsqlite3-dev \
-            libsdl2-mixer-dev
-      - name: Configure
-        run: |
-          cmake . -B build -G Ninja \
-            -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} \
-            -DCMAKE_EXPORT_COMPILE_COMMANDS=on
-      - name: Build
-        run: |
-          cmake --build build
-      - uses: ZedThree/clang-tidy-review@v0.8.4
+
+      - uses: ZedThree/clang-tidy-review@v0.9.0
         id: review
         with:
-          # Tell clang-tidy-review the base directory.
-          # This will get replaced by the new working
-          # directory inside the action
-          base_dir: ${{ matrix.base_dir }}
+          apt_packages: 'cmake,ninja-build,python3,g++,gettext,qtbase5-dev,libqt5svg5-dev,libkf5archive-dev,liblua5.3-dev,libsqlite3-dev,libsdl2-mixer-dev'
+
+          # Tell clang-tidy-review the build directory, so it finds the
+          # compilation database.
+          build_dir: build
diff --git a/client/client_main.cpp b/client/client_main.cpp
index 93e998e4ed..c9ee962f9a 100644
--- a/client/client_main.cpp
+++ b/client/client_main.cpp
@@ -585,17 +585,15 @@ int client_main(int argc, char *argv[])
   boot_help_texts(client_current_nation_set(), tileset_help(tileset));
 
   fill_topo_ts_default();
-
   if (!forced_tileset_name.isEmpty()) {
-    if (!tilespec_try_read(qUtf8Printable(forced_tileset_name), true, -1,
-                           true)) {
+    if (!tilespec_try_read(forced_tileset_name, true, -1)) {
       qCritical(_("Can't load requested tileset %s!"),
                 qUtf8Printable(forced_tileset_name));
       client_exit();
       return EXIT_FAILURE;
     }
   } else {
-    tilespec_try_read(gui_options.default_tileset_name, false, -1, true);
+    tilespec_try_read(QString(), false, -1);
   }
 
   audio_real_init(sound_set_name, music_set_name, sound_plugin_name);
diff --git a/client/connectdlg_common.cpp b/client/connectdlg_common.cpp
index f2974206db..8170a406be 100644
--- a/client/connectdlg_common.cpp
+++ b/client/connectdlg_common.cpp
@@ -200,7 +200,7 @@ static int find_next_free_port(int starting_port, int highest_port)
 bool client_start_server(const QString &user_name)
 {
   QStringList arguments;
-  QString trueFcser, ruleset, storage, port_buf, savesdir, scensdir;
+  QString trueFcser, storage, port_buf, savesdir, scensdir;
   char buf[512];
   int connect_tries = 0;
 
@@ -233,8 +233,6 @@ bool client_start_server(const QString &user_name)
     return false;
   }
 
-  ruleset = QString::fromUtf8(tileset_what_ruleset(tileset));
-
   // Set up the command-line parameters.
   port_buf = QString::number(internal_server_port);
   savesdir = QStringLiteral("%1/saves").arg(storage);
@@ -256,9 +254,6 @@ bool client_start_server(const QString &user_name)
   if (savefile.isEmpty()) {
     arguments << QStringLiteral("--file") << savefile;
   }
-  if (ruleset != nullptr) {
-    arguments << QStringLiteral("--ruleset") << ruleset;
-  }
 
   // Look for a server binary
   const QString server_name = QStringLiteral("freeciv21-server");
@@ -330,38 +325,6 @@ bool client_start_server(const QString &user_name)
     return false;
   }
 
-  /* We set the topology to match the view.
-   *
-   * When a typical player launches a game, he wants the map orientation to
-   * match the tileset orientation.  So if you use an isometric tileset you
-   * get an iso-map and for a classic tileset you get a classic map.  In
-   * both cases the map wraps in the X direction by default.
-   *
-   * This works with hex maps too now.  A hex map always has
-   * tileset_is_isometric(tileset) return TRUE.  An iso-hex map has
-   * tileset_hex_height(tileset) != 0, while a non-iso hex map
-   * has tileset_hex_width(tileset) != 0.
-   *
-   * Setting the option here is a bit of a hack, but so long as the client
-   * has sufficient permissions to do so (it doesn't have HACK access yet) it
-   * is safe enough.  Note that if you load a savegame the topology will be
-   * set but then overwritten during the load.
-   *
-   * Don't send it now, it will be sent to the server when receiving the
-   * server setting infos. */
-  {
-    char topobuf[16];
-
-    fc_strlcpy(topobuf, "WRAPX", sizeof(topobuf));
-    if (tileset_is_isometric(tileset) && 0 == tileset_hex_height(tileset)) {
-      fc_strlcat(topobuf, "|ISO", sizeof(topobuf));
-    }
-    if (0 < tileset_hex_width(tileset) || 0 < tileset_hex_height(tileset)) {
-      fc_strlcat(topobuf, "|HEX", sizeof(topobuf));
-    }
-    desired_settable_option_update("topology", topobuf, false);
-  }
-
   return true;
 }
 
diff --git a/client/options.cpp b/client/options.cpp
index f8ab84f64e..1f3d265132 100644
--- a/client/options.cpp
+++ b/client/options.cpp
@@ -88,7 +88,6 @@ struct client_options gui_options = {
 
     /** Migrations **/
     false, //.first_boot =
-    "\0",  //.default_tileset_name =
     "\0",  //.default_tileset_overhead_name =
     "\0",  //.default_tileset_iso_name =
     false, //.gui_qt_migrated_from_2_5 =
@@ -4418,11 +4417,6 @@ void options_load()
       secfile_lookup_bool_default(sf, gui_options.gui_qt_migrated_from_2_5,
                                   "%s.migration_qt_from_2_5", prefix);
 
-  str =
-      secfile_lookup_str_default(sf, nullptr, "client.default_tileset_name");
-  if (str != nullptr) {
-    sz_strlcpy(gui_options.default_tileset_name, str);
-  }
   str = secfile_lookup_str_default(sf, nullptr,
                                    "client.default_tileset_overhead_name");
   if (str != nullptr) {
@@ -4531,11 +4525,6 @@ void options_save(option_save_log_callback log_cb)
   client_options_iterate_all(poption) { client_option_save(poption, sf); }
   client_options_iterate_all_end;
 
-  if (gui_options.default_tileset_name[0] != '\0') {
-    secfile_insert_str(sf, gui_options.default_tileset_name,
-                       "client.default_tileset_name");
-  }
-
   message_options_save(sf, "client");
   options_dialogs_save(sf);
 
@@ -4878,10 +4867,6 @@ const char *tileset_name_for_topology(int topology_id)
     break;
   }
 
-  if (tsn == nullptr) {
-    tsn = gui_options.default_tileset_name;
-  }
-
   return tsn;
 }
 
@@ -4957,15 +4942,15 @@ void fill_topo_ts_default()
                sizeof(gui_options.default_tileset_square_name));
     } else {
       log_debug("Setting tileset for square topologies.");
-      tilespec_try_read(nullptr, false, 0, false);
+      tilespec_try_read(QString(), false, 0);
     }
   }
   if (is_ts_option_unset("default_tileset_hex_name")) {
     log_debug("Setting tileset for hex topology.");
-    tilespec_try_read(nullptr, false, TF_HEX, false);
+    tilespec_try_read(QString(), false, TF_HEX);
   }
   if (is_ts_option_unset("default_tileset_isohex_name")) {
     log_debug("Setting tileset for isohex topology.");
-    tilespec_try_read(nullptr, false, TF_ISO | TF_HEX, false);
+    tilespec_try_read(QString(), false, TF_ISO | TF_HEX);
   }
 }
diff --git a/client/options.h b/client/options.h
index 4311080d48..9d7a80e00d 100644
--- a/client/options.h
+++ b/client/options.h
@@ -62,9 +62,8 @@ struct client_options {
   bool save_options_on_exit;
 
   /** Migrations **/
-  bool first_boot;                /* There was no earlier options saved.
-                                   * This affects some migrations, but not all. */
-  char default_tileset_name[512]; // pre-2.6 had just this one tileset name
+  bool first_boot; /* There was no earlier options saved.
+                    * This affects some migrations, but not all. */
   char default_tileset_overhead_name[512]; /* 2.6 had separate tilesets for
                                               ... */
   char default_tileset_iso_name[512];      // ...overhead and iso topologies.
diff --git a/client/tilespec.cpp b/client/tilespec.cpp
index 0f74d267cd..feb1cd96d2 100644
--- a/client/tilespec.cpp
+++ b/client/tilespec.cpp
@@ -300,8 +300,6 @@ struct tileset {
 
   std::vector<tileset_log_entry> log;
 
-  char *for_ruleset;
-
   std::vector<std::unique_ptr<freeciv::layer>> layers;
   struct {
     freeciv::layer_special *background, *middleground, *foreground;
@@ -367,7 +365,7 @@ int focus_unit_state = 0;
 
 static bool tileset_update = false;
 
-static struct tileset *tileset_read_toplevel(const char *tileset_name,
+static struct tileset *tileset_read_toplevel(const QString &tileset_name,
                                              bool verbose, int topology_id);
 
 static bool load_river_sprites(struct tileset *t,
@@ -892,10 +890,8 @@ static void tileset_free_toplevel(struct tileset *t)
 
   delete[] t->summary;
   delete[] t->description;
-  delete[] t->for_ruleset;
   t->summary = nullptr;
   t->description = nullptr;
-  t->for_ruleset = nullptr;
 }
 
 /**
@@ -923,12 +919,12 @@ void tileset_free(struct tileset *t)
 
    Returns TRUE iff tileset with suggested tileset_name was loaded.
  */
-bool tilespec_try_read(const char *tileset_name, bool verbose, int topo_id,
-                       bool global_default)
+bool tilespec_try_read(const QString &tileset_name, bool verbose,
+                       int topo_id)
 {
   bool original;
 
-  if (tileset_name == nullptr
+  if (tileset_name.isEmpty()
       || !(tileset =
                tileset_read_toplevel(tileset_name, verbose, topo_id))) {
     QVector<QString> *list = fileinfolist(get_data_dirs(), TILESPEC_SUFFIX);
@@ -965,10 +961,6 @@ bool tilespec_try_read(const char *tileset_name, bool verbose, int topo_id,
   }
   option_set_default_ts(tileset);
 
-  if (global_default) {
-    sz_strlcpy(gui_options.default_tileset_name, tileset_basename(tileset));
-  }
-
   return original;
 }
 
@@ -985,32 +977,27 @@ bool tilespec_try_read(const char *tileset_name, bool verbose, int topo_id,
 
    Returns TRUE iff new tileset has been succesfully loaded.
  */
-bool tilespec_reread(const char *new_tileset_name,
-                     bool game_fully_initialized)
+bool tilespec_reread(const QString &name, bool game_fully_initialized)
 {
   int id;
-  struct tile *center_tile;
   enum client_states state = client_state();
-  const char *name = new_tileset_name ? new_tileset_name : tileset->name;
   bool new_tileset_in_use;
 
-  // Make local copies since these values may be freed down below
-  QString tileset_name = name;
-  QString old_name = tileset->name;
-
-  qInfo(_("Loading tileset \"%s\"."), qUtf8Printable(tileset_name));
+  qInfo(_("Loading tileset \"%s\"."), qUtf8Printable(name));
 
   /* Step 0:  Record old data.
    *
    * We record the current mapcanvas center, etc.
    */
-  center_tile = get_center_tile_mapcanvas();
+  auto center_tile = tileset ? get_center_tile_mapcanvas() : nullptr;
 
   /* Step 1:  Cleanup.
    *
    * Free old tileset.
    */
+  const char *old_name = nullptr;
   if (tileset) {
+    old_name = tileset->name;
     tileset_free(tileset);
   }
 
@@ -1018,14 +1005,14 @@ bool tilespec_reread(const char *new_tileset_name,
    *
    * We read in the new tileset.  This should be pretty straightforward.
    */
-  tileset = tileset_read_toplevel(qUtf8Printable(tileset_name), false, -1);
+  tileset = tileset_read_toplevel(name, false, -1);
   if (tileset != nullptr) {
     new_tileset_in_use = true;
   } else {
     new_tileset_in_use = false;
 
-    if (!(tileset =
-              tileset_read_toplevel(qUtf8Printable(old_name), false, -1))) {
+    if (old_name
+        && !(tileset = tileset_read_toplevel(old_name, false, -1))) {
       // Always fails.
       fc_assert_exit_msg(nullptr != tileset,
                          "Failed to re-read the currently loaded tileset.");
@@ -1143,10 +1130,6 @@ void tilespec_reread_callback(struct option *poption)
 
   tileset_name = option_str_get(poption);
 
-  /* As it's going to be 'current' tileset, make it global default if
-   * options saved. */
-  sz_strlcpy(gui_options.default_tileset_name, tileset_name);
-
   fc_assert_ret(nullptr != tileset_name && tileset_name[0] != '\0');
   tileset_update = true;
   tilespec_reread(tileset_name, client.conn.established);
@@ -1160,10 +1143,10 @@ void tilespec_reread_callback(struct option *poption)
 
    See tilespec_reread() for details.
  */
-void tilespec_reread_frozen_refresh(const char *tname)
+void tilespec_reread_frozen_refresh(const QString &name)
 {
   tileset_update = true;
-  tilespec_reread(tname, true);
+  tilespec_reread(name, true);
   tileset_update = false;
   menus_init();
 }
@@ -1594,7 +1577,7 @@ static void tileset_add_layer(struct tileset *t, mapview_layer layer)
    intro files.
    topology_id of -1 means any topology is acceptable.
  */
-static struct tileset *tileset_read_toplevel(const char *tileset_name,
+static struct tileset *tileset_read_toplevel(const QString &tileset_name,
                                              bool verbose, int topology_id)
 {
   struct section_file *file;
@@ -1618,7 +1601,7 @@ static struct tileset *tileset_read_toplevel(const char *tileset_name,
   fname = tilespec_fullname(tileset_name);
   if (!fname) {
     if (verbose) {
-      qCritical("Can't find tileset \"%s\".", tileset_name);
+      qCritical("Can't find tileset \"%s\".", qUtf8Printable(tileset_name));
     }
     return nullptr;
   }
@@ -1685,14 +1668,7 @@ static struct tileset *tileset_read_toplevel(const char *tileset_name,
     }
   }
 
-  tstr = secfile_lookup_str_default(file, nullptr, "tilespec.for_ruleset");
-  if (tstr != nullptr) {
-    t->for_ruleset = fc_strdup(tstr);
-  } else {
-    t->for_ruleset = nullptr;
-  }
-
-  sz_strlcpy(t->name, tileset_name);
+  sz_strlcpy(t->name, tileset_name.toUtf8().data());
   if (!secfile_lookup_int(file, &t->priority, "tilespec.priority")
       || !secfile_lookup_bool(file, &is_hex, "tilespec.is_hex")) {
     qCritical("Tileset \"%s\" invalid: %s", t->name, secfile_error());
@@ -5682,11 +5658,6 @@ const char *tileset_summary(struct tileset *t) { return t->summary; }
  */
 const char *tileset_description(struct tileset *t) { return t->description; }
 
-/**
-   Return what ruleset this tileset is primarily meant for
- */
-char *tileset_what_ruleset(struct tileset *t) { return t->for_ruleset; }
-
 /**
    Return tileset topology index
  */
diff --git a/client/tilespec.h b/client/tilespec.h
index 40d7c1dfdc..ece2ab6fe0 100644
--- a/client/tilespec.h
+++ b/client/tilespec.h
@@ -117,11 +117,11 @@ bool tileset_has_error(const struct tileset *t);
 
 void finish_loading_sprites(struct tileset *t);
 
-bool tilespec_try_read(const char *tileset_name, bool verbose, int topo_id,
-                       bool global_default);
-bool tilespec_reread(const char *tileset_name, bool game_fully_initialized);
+bool tilespec_try_read(const QString &name, bool verbose, int topo_id);
+bool tilespec_reread(const QString &tileset_name,
+                     bool game_fully_initialized);
 void tilespec_reread_callback(struct option *poption);
-void tilespec_reread_frozen_refresh(const char *tname);
+void tilespec_reread_frozen_refresh(const QString &name);
 
 void tileset_setup_specialist_type(struct tileset *t, Specialist_type_id id);
 void tileset_setup_unit_type(struct tileset *t, struct unit_type *punittype);
@@ -318,6 +318,5 @@ const char *tileset_name_get(struct tileset *t);
 const char *tileset_version(struct tileset *t);
 const char *tileset_summary(struct tileset *t);
 const char *tileset_description(struct tileset *t);
-char *tileset_what_ruleset(struct tileset *t);
 int tileset_topo_index(struct tileset *t);
 help_item *tileset_help(struct tileset *t);
diff --git a/data/alio.tilespec b/data/alio.tilespec
index 8e9edb64d9..0b438724ab 100644
--- a/data/alio.tilespec
+++ b/data/alio.tilespec
@@ -24,9 +24,6 @@ Tileset containing graphics suitable for playing with alien ruleset.\
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-for_ruleset = "alien"
-
 ; Basic tile sizes:
 normal_tile_width  = 126
 normal_tile_height = 64
diff --git a/data/amplio.tilespec b/data/amplio.tilespec
index 89dcb0ca78..59138bba2a 100644
--- a/data/amplio.tilespec
+++ b/data/amplio.tilespec
@@ -18,9 +18,6 @@ summary = _("Older variant of the current default tileset, Amplio2")
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 96
 normal_tile_height = 48
diff --git a/data/amplio2.tilespec b/data/amplio2.tilespec
index 12a70cf061..28424e0711 100644
--- a/data/amplio2.tilespec
+++ b/data/amplio2.tilespec
@@ -18,9 +18,6 @@ summary = _("Large isometric tileset.")
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 96
 normal_tile_height = 48
diff --git a/data/cimpletoon.tilespec b/data/cimpletoon.tilespec
index fe1d0ca975..04d7305783 100644
--- a/data/cimpletoon.tilespec
+++ b/data/cimpletoon.tilespec
@@ -21,9 +21,6 @@ direction the unit is facing.\
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 96
 normal_tile_height = 48
diff --git a/data/hex2t.tilespec b/data/hex2t.tilespec
index 117d3fadae..7121ad8da6 100644
--- a/data/hex2t.tilespec
+++ b/data/hex2t.tilespec
@@ -18,9 +18,6 @@ summary = _("Small hex tileset.")
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 40
 normal_tile_height = 72
diff --git a/data/hexemplio.tilespec b/data/hexemplio.tilespec
index 2c4e4a7029..a92ea0752f 100644
--- a/data/hexemplio.tilespec
+++ b/data/hexemplio.tilespec
@@ -20,9 +20,6 @@ summary = _("Large iso-hex tileset, similar to Amplio.")
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 126
 normal_tile_height = 64
diff --git a/data/isophex.tilespec b/data/isophex.tilespec
index 1e28afbe89..01906fc954 100644
--- a/data/isophex.tilespec
+++ b/data/isophex.tilespec
@@ -18,9 +18,6 @@ summary = _("Small iso-hex tileset.")
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 64
 normal_tile_height = 32
diff --git a/data/isotrident.tilespec b/data/isotrident.tilespec
index ce8738b8cb..d10820a85f 100644
--- a/data/isotrident.tilespec
+++ b/data/isotrident.tilespec
@@ -18,9 +18,6 @@ summary = _("Isometric tileset based on Trident tileset.")
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 64
 normal_tile_height = 32
diff --git a/data/toonhex.tilespec b/data/toonhex.tilespec
index d9ca51597d..000b568dfd 100644
--- a/data/toonhex.tilespec
+++ b/data/toonhex.tilespec
@@ -22,9 +22,6 @@ and Cimpletoon's units with orientation.")
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 126
 normal_tile_height = 64
diff --git a/data/trident.tilespec b/data/trident.tilespec
index dc6aea0e4d..3a278c9774 100644
--- a/data/trident.tilespec
+++ b/data/trident.tilespec
@@ -17,9 +17,6 @@ summary = _("Small overhead tileset.")
 ; TODO: add more overall information fields on tiles,
 ; eg, authors, colors, etc.
 
-; What is the primary ruleset this tileset is meant for.
-;for_ruleset = ""
-
 ; Basic tile sizes:
 normal_tile_width  = 30
 normal_tile_height = 30