diff --git a/res/textures/menubg.png b/res/textures/menubg.png
index 86d77d8e0..e3342a02a 100644
Binary files a/res/textures/menubg.png and b/res/textures/menubg.png differ
diff --git a/src/content/ContentIndexLUT.cpp b/src/content/ContentIndexLUT.cpp
deleted file mode 100644
index 8d9df8407..000000000
--- a/src/content/ContentIndexLUT.cpp
+++ /dev/null
@@ -1,69 +0,0 @@
-#include "ContentIndexLUT.h"
-
-#include <iostream>
-#include <memory>
-
-#include "Content.h"
-#include "../constants.h"
-#include "../files/files.h"
-#include "../coders/json.h"
-#include "../voxels/Block.h"
-
-using std::string;
-using std::unique_ptr;
-using std::filesystem::path;
-
-ContentIndexLUT::ContentIndexLUT(size_t blocksCount, const Content* content) {
-    blocks = new blockid_t[blocksCount];
-    blockNames = new string[blocksCount];
-    for (size_t i = 0; i < blocksCount; i++) {
-        blocks[i] = i;
-    }
-
-    ContentIndices* indices = content->indices;
-    for (size_t i = 0; i < indices->countBlockDefs(); i++) {
-        blockNames[i] = indices->getBlockDef(i)->name;
-    }
-}
-
-ContentIndexLUT::~ContentIndexLUT() {
-    delete[] blockNames;
-    delete[] blocks;
-}
-
-ContentIndexLUT* ContentIndexLUT::create(const path& filename, const Content* content) {
-    auto& indices = content->indices;
-    unique_ptr<json::JObject> root(files::read_json(filename));
-    json::JArray* blocksarr = root->arr("blocks");
-
-    size_t blocks_c = blocksarr 
-                       ? std::max(blocksarr->size(), indices->countBlockDefs()) 
-                       : indices->countBlockDefs();
-    
-    unique_ptr<ContentIndexLUT> lut(new ContentIndexLUT(blocks_c, content));
-
-    bool conflicts = false;
-
-    // TODO: implement world files convert feature using ContentIndexLUT report
-    for (size_t i = 0; i < blocksarr->size(); i++) {
-        string name = blocksarr->str(i);
-        Block* def = content->findBlock(name);
-        if (def) {
-            if (i != def->rt.id) {
-                std::cerr << "block id has changed from ";
-                std::cerr << def->rt.id << " to " << i << std::endl;
-                conflicts = true;
-            }
-            lut->setBlock(i, name, def->rt.id);
-        } else {
-            std::cerr << "unknown block: " << name << std::endl;
-            lut->setBlock(i, name, i);   
-            conflicts = true;
-        }
-    }
-    if (conflicts) {
-        return lut.release();
-    } else {
-        return nullptr;
-    }
-}
diff --git a/src/content/ContentIndexLUT.h b/src/content/ContentIndexLUT.h
deleted file mode 100644
index 37bb7df82..000000000
--- a/src/content/ContentIndexLUT.h
+++ /dev/null
@@ -1,33 +0,0 @@
-#ifndef CONTENT_CONTENT_INDEX_LUT_H_
-#define CONTENT_CONTENT_INDEX_LUT_H_
-
-#include "../typedefs.h"
-#include <string>
-#include <filesystem>
-
-class Content;
-
-/* Content indices lookup table or report 
-   used to convert world with different indices
-   Building with indices.json */
-class ContentIndexLUT {
-    blockid_t* blocks;
-    std::string* blockNames;
-public:
-    ContentIndexLUT(size_t blocks, const Content* content);
-    ~ContentIndexLUT();
-
-    inline blockid_t getBlockId(blockid_t index) {
-        return blocks[index];
-    }
-
-    inline void setBlock(blockid_t index, std::string name, blockid_t id) {
-        blocks[index] = id;
-        blockNames[index] = name;
-    }
-
-    static ContentIndexLUT* create(const std::filesystem::path& filename, 
-                                   const Content* content);
-};
-
-#endif // CONTENT_CONTENT_INDEX_LUT_H_
diff --git a/src/content/ContentLUT.cpp b/src/content/ContentLUT.cpp
new file mode 100644
index 000000000..7a0d6eb8e
--- /dev/null
+++ b/src/content/ContentLUT.cpp
@@ -0,0 +1,59 @@
+#include "ContentLUT.h"
+
+#include <memory>
+
+#include "Content.h"
+#include "../constants.h"
+#include "../files/files.h"
+#include "../coders/json.h"
+#include "../voxels/Block.h"
+
+using std::string;
+using std::unique_ptr;
+using std::make_unique;
+using std::filesystem::path;
+
+#include <iostream>
+
+ContentLUT::ContentLUT(size_t blocksCount, const Content* content) {
+    ContentIndices* indices = content->indices;
+    for (size_t i = 0; i < blocksCount; i++) {
+        blocks.push_back(i);
+    }
+    for (size_t i = 0; i < indices->countBlockDefs(); i++) {
+        blockNames.push_back(indices->getBlockDef(i)->name);
+    }
+
+        for (size_t i = indices->countBlockDefs(); i < blocksCount; i++) {
+        blockNames.push_back("");
+    }
+}
+
+ContentLUT* ContentLUT::create(const path& filename, 
+                               const Content* content) {
+    unique_ptr<json::JObject> root(files::read_json(filename));
+    json::JArray* blocksarr = root->arr("blocks");
+
+    auto& indices = content->indices;
+    size_t blocks_c = blocksarr 
+                      ? std::max(blocksarr->size(), indices->countBlockDefs()) 
+                      : indices->countBlockDefs();
+    
+    auto lut = make_unique<ContentLUT>(blocks_c, content);
+    if (blocksarr) {
+        for (size_t i = 0; i < blocksarr->size(); i++) {
+            string name = blocksarr->str(i);
+            Block* def = content->findBlock(name);
+            if (def) {
+                lut->setBlock(i, name, def->rt.id);
+            } else {
+                lut->setBlock(i, name, BLOCK_VOID);   
+            }
+        }
+    }
+    if (lut->hasContentReorder() || lut->hasMissingContent()) {
+        return lut.release();
+    } else {
+        return nullptr;
+    }
+}
diff --git a/src/content/ContentLUT.h b/src/content/ContentLUT.h
new file mode 100644
index 000000000..4da4df78e
--- /dev/null
+++ b/src/content/ContentLUT.h
@@ -0,0 +1,58 @@
+#ifndef CONTENT_CONTENT_LUT_H_
+#define CONTENT_CONTENT_LUT_H_
+
+#include <string>
+#include <vector>
+#include <filesystem>
+
+#include "../typedefs.h"
+#include "../constants.h"
+
+class Content;
+
+/* Content indices lookup table or report 
+   used to convert world with different indices
+   Building with indices.json */
+class ContentLUT {
+    std::vector<blockid_t> blocks;
+    std::vector<std::string> blockNames;
+
+    bool reorderContent = false;
+    bool missingContent = false;
+public:
+    ContentLUT(size_t blocks, const Content* content);
+
+    inline const std::string& getBlockName(blockid_t index) const {
+        return blockNames[index];
+    }
+
+    inline blockid_t getBlockId(blockid_t index) const {
+        return blocks[index];
+    }
+
+    inline void setBlock(blockid_t index, std::string name, blockid_t id) {
+        blocks[index] = id;
+        blockNames[index] = name;
+        if (id == BLOCK_VOID) {
+            missingContent = true;
+        } else if (index != id) {
+            reorderContent = true;
+        }
+    }
+
+    static ContentLUT* create(const std::filesystem::path& filename, 
+                                   const Content* content);
+    
+    inline bool hasContentReorder() const {
+        return reorderContent;
+    }
+    inline bool hasMissingContent() const {
+        return missingContent;
+    }
+
+    inline size_t countBlocks() const {
+        return blocks.size();
+    }
+};
+
+#endif // CONTENT_CONTENT_LUT_H_
diff --git a/src/files/WorldConverter.cpp b/src/files/WorldConverter.cpp
new file mode 100644
index 000000000..3c8c7b355
--- /dev/null
+++ b/src/files/WorldConverter.cpp
@@ -0,0 +1,71 @@
+#include "WorldConverter.h"
+
+#include <memory>
+#include <iostream>
+#include <stdexcept>
+#include "WorldFiles.h"
+#include "../voxels/Chunk.h"
+#include "../content/ContentLUT.h"
+
+namespace fs = std::filesystem;
+using std::string;
+using std::unique_ptr;
+using fs::path;
+
+WorldConverter::WorldConverter(path folder, 
+                               const Content* content, 
+                               const ContentLUT* lut) 
+    : lut(lut), content(content) {
+    DebugSettings settings;
+    wfile = new WorldFiles(folder, settings);
+
+    path regionsFolder = wfile->getRegionsFolder();
+    if (!fs::is_directory(regionsFolder)) {
+        std::cerr << "nothing to convert" << std::endl;
+        return;
+    }
+    for (auto file : fs::directory_iterator(regionsFolder)) {
+        regions.push(file.path());
+    }
+}
+
+WorldConverter::~WorldConverter() {
+    delete wfile;
+}
+
+bool WorldConverter::hasNext() const {
+    return !regions.empty();
+}
+
+void WorldConverter::convertNext() {
+    if (!hasNext()) {
+        throw std::runtime_error("no more regions to convert");
+    }
+    path regfile = regions.front();
+    regions.pop();
+    if (!fs::is_regular_file(regfile))
+        return;
+    int x, y;
+    string name = regfile.stem().string();
+    if (!WorldFiles::parseRegionFilename(name, x, y)) {
+        std::cerr << "could not parse name " << name << std::endl;
+        return;
+    }
+    std::cout << "converting region " << name << std::endl;
+    for (uint cz = 0; cz < REGION_SIZE; cz++) {
+        for (uint cx = 0; cx < REGION_SIZE; cx++) {
+            int gx = cx + x * REGION_SIZE;
+            int gz = cz + y * REGION_SIZE;
+            unique_ptr<ubyte[]> data (wfile->getChunk(gx, gz));
+            if (data == nullptr)
+                continue;
+            Chunk::convert(data.get(), lut);
+            wfile->put(gx, gz, data.get());
+        }
+    }
+}
+
+void WorldConverter::write() {
+    std::cout << "writing world" << std::endl;
+    wfile->write(nullptr, content);
+}
diff --git a/src/files/WorldConverter.h b/src/files/WorldConverter.h
new file mode 100644
index 000000000..d18c37e9f
--- /dev/null
+++ b/src/files/WorldConverter.h
@@ -0,0 +1,26 @@
+#ifndef FILES_WORLD_CONVERTER_H_
+#define FILES_WORLD_CONVERTER_H_
+
+#include <queue>
+#include <filesystem>
+
+class Content;
+class ContentLUT;
+class WorldFiles;
+
+class WorldConverter {
+    WorldFiles* wfile;
+    const ContentLUT* const lut;
+    const Content* const content;
+    std::queue<std::filesystem::path> regions;
+public:
+    WorldConverter(std::filesystem::path folder, const Content* content, const ContentLUT* lut);
+    ~WorldConverter();
+
+    bool hasNext() const;
+    void convertNext();
+
+    void write();
+};
+
+#endif // FILES_WORLD_CONVERTER_H_
diff --git a/src/files/WorldFiles.cpp b/src/files/WorldFiles.cpp
index ffb264712..b106ba378 100644
--- a/src/files/WorldFiles.cpp
+++ b/src/files/WorldFiles.cpp
@@ -122,7 +122,7 @@ WorldRegion* WorldFiles::getOrCreateRegion(
 	return region;
 }
 
-ubyte* WorldFiles::compress(ubyte* src, size_t srclen, size_t& len) {
+ubyte* WorldFiles::compress(const ubyte* src, size_t srclen, size_t& len) {
 	len = extrle::encode(src, srclen, compressionBuffer);
 	ubyte* data = new ubyte[len];
 	for (size_t i = 0; i < len; i++) {
@@ -131,12 +131,27 @@ ubyte* WorldFiles::compress(ubyte* src, size_t srclen, size_t& len) {
 	return data;
 }
 
-ubyte* WorldFiles::decompress(ubyte* src, size_t srclen, size_t dstlen) {
+ubyte* WorldFiles::decompress(const ubyte* src, size_t srclen, size_t dstlen) {
 	ubyte* decompressed = new ubyte[dstlen];
 	extrle::decode(src, srclen, decompressed);
 	return decompressed;
 }
 
+void WorldFiles::put(int x, int z, const ubyte* voxelData) {
+    int regionX = floordiv(x, REGION_SIZE);
+	int regionZ = floordiv(z, REGION_SIZE);
+	int localX = x - (regionX * REGION_SIZE);
+	int localZ = z - (regionZ * REGION_SIZE);
+
+	/* Writing Voxels */ {
+		WorldRegion* region = getOrCreateRegion(regions, regionX, regionZ);
+		region->setUnsaved(true);
+		size_t compressedSize;
+		ubyte* data = compress(voxelData, CHUNK_DATA_LEN, compressedSize);
+		region->put(localX, localZ, data, compressedSize);
+	}
+}
+
 void WorldFiles::put(Chunk* chunk){
 	assert(chunk != nullptr);
 
@@ -176,6 +191,21 @@ path WorldFiles::getRegionFilename(int x, int y) const {
 	return path(filename);
 }
 
+bool WorldFiles::parseRegionFilename(const string& name, int& x, int& y) {
+    size_t sep = name.find('_');
+    if (sep == string::npos || sep == 0 || sep == name.length()-1)
+        return false;
+    try {
+        x = std::stoi(name.substr(0, sep));
+        y = std::stoi(name.substr(sep+1));
+    } catch (std::invalid_argument& err) {
+        return false;
+    } catch (std::out_of_range& err) {
+        return false;
+    }
+    return true;
+}
+
 path WorldFiles::getPlayerFile() const {
 	return directory/path("player.json");
 }
@@ -338,7 +368,8 @@ void WorldFiles::write(const World* world, const Content* content) {
 			fs::create_directories(directory);
 		}
 	}
-	writeWorldInfo(world);
+    if (world)
+	    writeWorldInfo(world);
 	if (generatorTestMode)
 		return;
 	writeIndices(content->indices);
diff --git a/src/files/WorldFiles.h b/src/files/WorldFiles.h
index 8d78c2e07..e3e53e7a3 100644
--- a/src/files/WorldFiles.h
+++ b/src/files/WorldFiles.h
@@ -49,7 +49,6 @@ class WorldRegion {
 
 class WorldFiles {
 	void writeWorldInfo(const World* world);
-	std::filesystem::path getRegionsFolder() const;
 	std::filesystem::path getLightsFolder() const;
 	std::filesystem::path getRegionFilename(int x, int y) const;
 	std::filesystem::path getPlayerFile() const;
@@ -74,14 +73,14 @@ class WorldFiles {
 	   @param src source buffer
 	   @param srclen length of source buffer
 	   @param len (out argument) length of result buffer */
-	ubyte* compress(ubyte* src, size_t srclen, size_t& len);
+	ubyte* compress(const ubyte* src, size_t srclen, size_t& len);
 
 	/* Decompress buffer with extrle
 	   @param src compressed buffer
 	   @param srclen length of compressed buffer
 	   @param dstlen max expected length of source buffer
 	*/
-	ubyte* decompress(ubyte* src, size_t srclen, size_t dstlen);
+	ubyte* decompress(const ubyte* src, size_t srclen, size_t dstlen);
 
 	ubyte* readChunkData(int x, int y, 
 						uint32_t& length, 
@@ -94,6 +93,9 @@ class WorldFiles {
 				   const std::filesystem::path& folder,
 				   int x, int z);
 public:
+    static bool parseRegionFilename(const std::string& name, int& x, int& y);
+    std::filesystem::path getRegionsFolder() const;
+
 	std::unordered_map<glm::ivec2, WorldRegion*> regions;
 	std::unordered_map<glm::ivec2, WorldRegion*> lights;
 	std::filesystem::path directory;
@@ -105,8 +107,10 @@ class WorldFiles {
 	~WorldFiles();
 
 	void put(Chunk* chunk);
-	ubyte* getChunk(int x, int y);
-	light_t* getLights(int x, int y);
+    void put(int x, int z, const ubyte* voxelData);
+
+	ubyte* getChunk(int x, int z);
+	light_t* getLights(int x, int z);
 
 	bool readWorldInfo(World* world);
 	bool readPlayer(Player* player);
@@ -115,6 +119,7 @@ class WorldFiles {
 					 WorldRegion* entry, 
 					 std::filesystem::path file);
 	void writePlayer(Player* player);
+    /* @param world world info to save (nullable) */
 	void write(const World* world, const Content* content);
 	void writeIndices(const ContentIndices* indices);
 };
diff --git a/src/frontend/gui/GUI.cpp b/src/frontend/gui/GUI.cpp
index 2477c141c..953a23225 100644
--- a/src/frontend/gui/GUI.cpp
+++ b/src/frontend/gui/GUI.cpp
@@ -29,6 +29,7 @@ GUI::GUI() {
 
     menu = new PagesControl();
     container->add(menu);
+    container->scrollable(false);
 }
 
 GUI::~GUI() {
@@ -166,4 +167,14 @@ shared_ptr<UINode> GUI::get(string name) {
 
 void GUI::remove(string name) {
     storage.erase(name);
-}
\ No newline at end of file
+}
+
+void GUI::setFocus(shared_ptr<UINode> node) {
+    if (focus) {
+        focus->defocus();
+    }
+    focus = node;
+    if (focus) {
+        focus->focus(this);
+    }
+}
diff --git a/src/frontend/gui/GUI.h b/src/frontend/gui/GUI.h
index 0ec5c04bd..e2dd55cb0 100644
--- a/src/frontend/gui/GUI.h
+++ b/src/frontend/gui/GUI.h
@@ -80,6 +80,7 @@ namespace gui {
         void store(std::string name, std::shared_ptr<UINode> node);
         std::shared_ptr<UINode> get(std::string name);
         void remove(std::string name);
+        void setFocus(std::shared_ptr<UINode> node);
     };
 }
 
diff --git a/src/frontend/gui/gui_util.cpp b/src/frontend/gui/gui_util.cpp
index df902c327..8d5277343 100644
--- a/src/frontend/gui/gui_util.cpp
+++ b/src/frontend/gui/gui_util.cpp
@@ -37,19 +37,20 @@ void guiutil::alert(GUI* gui, wstring text, gui::runnable on_hidden) {
     menu->set("<alert>");
 }
 
-void guiutil::confirm(GUI* gui, wstring text, gui::runnable on_confirm) {
+void guiutil::confirm(GUI* gui, wstring text, gui::runnable on_confirm,
+                      wstring yestext, wstring notext) {
     PagesControl* menu = gui->getMenu();
-    Panel* panel = new Panel(vec2(500, 200), vec4(8.0f), 8.0f);
+    Panel* panel = new Panel(vec2(600, 200), vec4(8.0f), 8.0f);
     panel->color(vec4(0.0f, 0.0f, 0.0f, 0.5f));
     panel->add(new Label(text));
-    Panel* subpanel = new Panel(vec2(500, 53));
+    Panel* subpanel = new Panel(vec2(600, 53));
     subpanel->color(vec4(0));
-    subpanel->add((new Button(L"Yes", vec4(8.0f)))->listenAction([=](GUI*){
+    subpanel->add((new Button(yestext, vec4(8.0f)))->listenAction([=](GUI*){
         if (on_confirm)
             on_confirm();
         menu->back();
     }));
-    subpanel->add((new Button(L"No", vec4(8.0f)))->listenAction([=](GUI*){
+    subpanel->add((new Button(notext, vec4(8.0f)))->listenAction([=](GUI*){
         menu->back();
     }));
     panel->add(subpanel);
diff --git a/src/frontend/gui/gui_util.h b/src/frontend/gui/gui_util.h
index 3bfb50a5b..306401782 100644
--- a/src/frontend/gui/gui_util.h
+++ b/src/frontend/gui/gui_util.h
@@ -12,7 +12,8 @@ namespace guiutil {
     gui::Button* backButton(gui::PagesControl* menu);
     gui::Button* gotoButton(std::wstring text, std::string page, gui::PagesControl* menu);
     void alert(gui::GUI* gui, std::wstring text, gui::runnable on_hidden=nullptr);
-    void confirm(gui::GUI* gui, std::wstring text, gui::runnable on_confirm=nullptr);
+    void confirm(gui::GUI* gui, std::wstring text, gui::runnable on_confirm=nullptr,
+                 std::wstring yestext=L"Yes", std::wstring notext=L"No");
 }
 
 #endif // FRONTEND_GUI_GUI_UTIL_H_
diff --git a/src/frontend/menu.cpp b/src/frontend/menu.cpp
index a1de88c96..3d90fee7b 100644
--- a/src/frontend/menu.cpp
+++ b/src/frontend/menu.cpp
@@ -13,11 +13,14 @@
 #include "screens.h"
 #include "../util/stringutil.h"
 #include "../files/engine_paths.h"
+#include "../files/WorldConverter.h"
 #include "../world/World.h"
 #include "../window/Events.h"
 #include "../window/Window.h"
 #include "../engine.h"
 #include "../settings.h"
+#include "../content/Content.h"
+#include "../content/ContentLUT.h"
 
 #include "gui/gui_util.h"
 
@@ -25,12 +28,69 @@ using glm::vec2;
 using glm::vec4;
 using std::string;
 using std::wstring;
+using std::make_unique;
+using std::unique_ptr;
 using std::shared_ptr;
 using std::filesystem::path;
 using std::filesystem::u8path;
 using std::filesystem::directory_iterator;
 using namespace gui;
 
+
+void show_content_missing(GUI* gui, const Content* content, ContentLUT* lut) {
+    PagesControl* menu = gui->getMenu();
+    Panel* panel = new Panel(vec2(500, 200), vec4(8.0f), 8.0f);
+    panel->color(vec4(0.0f, 0.0f, 0.0f, 0.5f));
+    panel->add(new Label(L"Content missing!"));
+
+    Panel* subpanel = new Panel(vec2(500, 100));
+    subpanel->color(vec4(0.0f, 0.0f, 0.0f, 0.5f));
+
+    for (size_t i = 0; i < lut->countBlocks(); i++) {
+        // missing block
+        if (lut->getBlockId(i) == BLOCK_VOID) {
+            auto name = lut->getBlockName(i);
+            Panel* hpanel = new Panel(vec2(500, 30));
+            hpanel->color(vec4(0.0f));
+            hpanel->orientation(Orientation::horizontal);
+            
+            Label* namelabel = new Label(util::str2wstr_utf8(name));
+            namelabel->color(vec4(1.0f, 0.2f, 0.2f, 0.5f));
+
+            Label* typelabel = new Label(L"[block]");
+            typelabel->color(vec4(0.5f));
+            hpanel->add(typelabel);
+            hpanel->add(namelabel);
+            subpanel->add(hpanel);
+        }
+    }
+    subpanel->maxLength(400);
+    panel->add(subpanel);
+
+    panel->add((new Button(L"Back to Main Menu", vec4(8.0f)))->listenAction([=](GUI*){
+        menu->back();
+    }));
+    panel->refresh();
+    menu->add("missing-content", panel);
+    menu->set("missing-content");
+}
+
+void show_convert_request(GUI* gui, const Content* content, ContentLUT* lut,
+                          path folder) {
+    guiutil::confirm(gui, L"Content indices have changed! Convert "
+                     +util::str2wstr_utf8(folder.string())+L"?",
+    [=]() {
+        std::cout << "Convert the world: " << folder.string() << std::endl;    
+        // TODO: add multithreading here
+        auto converter = make_unique<WorldConverter>(folder, content, lut);
+        while (converter->hasNext()) {
+            converter->convertNext();
+        }
+        converter->write();
+        delete lut;
+    }, L"Yes", L"Cancel");
+}
+
 Panel* create_main_menu_panel(Engine* engine, PagesControl* menu) {
     EnginePaths* paths = engine->getPaths();
 
@@ -40,7 +100,7 @@ Panel* create_main_menu_panel(Engine* engine, PagesControl* menu) {
     panel->add(guiutil::gotoButton(L"New World", "new-world", menu));
 
     Panel* worldsPanel = new Panel(vec2(390, 200), vec4(5.0f));
-    worldsPanel->color(vec4(0.1f));
+    worldsPanel->color(vec4(1.0f, 1.0f, 1.0f, 0.07f));
     worldsPanel->maxLength(400);
     path worldsFolder = paths->getWorldsFolder();
     if (std::filesystem::is_directory(worldsFolder)) {
@@ -51,14 +111,25 @@ Panel* create_main_menu_panel(Engine* engine, PagesControl* menu) {
             string name = entry.path().filename().string();
             Button* button = new Button(util::str2wstr_utf8(name), 
                                         vec4(10.0f, 8.0f, 10.0f, 8.0f));
-            button->color(vec4(0.5f));
-            button->listenAction([=](GUI*) {
-                EngineSettings& settings = engine->getSettings();
-
+            button->color(vec4(1.0f, 1.0f, 1.0f, 0.1f));
+            button->listenAction([=](GUI* gui) {
+                auto* content = engine->getContent();
+                auto& settings = engine->getSettings();
                 auto folder = paths->getWorldsFolder()/u8path(name);
-                Level* level = World::load(folder, settings, engine->getContent());
-                auto screen = new LevelScreen(engine, level);
-                engine->setScreen(shared_ptr<Screen>(screen));
+                std::filesystem::create_directories(folder);
+                ContentLUT* lut = World::checkIndices(folder, content);
+                if (lut) {
+                    if (lut->hasMissingContent()) {
+                        show_content_missing(gui, content, lut);
+                        delete lut;
+                    } else {
+                        show_convert_request(gui, content, lut, folder);
+                    }
+                } else {
+                    Level* level = World::load(folder, settings, content);
+                    auto screen = new LevelScreen(engine, level);
+                    engine->setScreen(shared_ptr<Screen>(screen));
+                }
             });
             worldsPanel->add(button);
         }
@@ -140,12 +211,13 @@ Panel* create_new_world_panel(Engine* engine, PagesControl* menu) {
                 seed = hash(seedstr);
             }
             std::cout << "world seed: " << seed << std::endl;
-            
-            EngineSettings& settings = engine->getSettings();
 
             auto folder = paths->getWorldsFolder()/u8path(nameutf8);
-            std::filesystem::create_directories(folder);
-            Level* level = World::create(nameutf8, folder, seed, settings, engine->getContent());
+            Level* level = World::create(nameutf8, 
+                                         folder, 
+                                         seed, 
+                                         engine->getSettings(), 
+                                         engine->getContent());
             auto screen = new LevelScreen(engine, level);
             engine->setScreen(shared_ptr<Screen>(screen));
         });
@@ -207,7 +279,6 @@ Panel* create_settings_panel(Engine* engine, PagesControl* menu) {
     Panel* panel = new Panel(vec2(400, 200), vec4(5.0f), 1.0f);
     panel->color(vec4(0.0f));
 
-    // TODO: simplify repeating code for trackbars
     /* Load Distance setting track bar */{
         panel->add((new Label(L""))->textSupplier([=]() {
             return L"Load Distance: " + 
diff --git a/src/voxels/Chunk.cpp b/src/voxels/Chunk.cpp
index f1d86cc68..f1efaf33d 100644
--- a/src/voxels/Chunk.cpp
+++ b/src/voxels/Chunk.cpp
@@ -1,5 +1,6 @@
 #include "Chunk.h"
 #include "voxel.h"
+#include "../content/ContentLUT.h"
 #include "../lighting/Lightmap.h"
 
 Chunk::Chunk(int xpos, int zpos) : x(xpos), z(zpos){
@@ -80,3 +81,10 @@ bool Chunk::decode(ubyte* data) {
 	}
 	return true;
 }
+
+void Chunk::convert(ubyte* data, const ContentLUT* lut) {
+    for (size_t i = 0; i < CHUNK_VOL; i++) {
+        blockid_t id = data[i];
+		data[i] = lut->getBlockId(id);
+    }
+}
diff --git a/src/voxels/Chunk.h b/src/voxels/Chunk.h
index 690a732ef..8d9157545 100644
--- a/src/voxels/Chunk.h
+++ b/src/voxels/Chunk.h
@@ -16,6 +16,7 @@ struct ChunkFlag{
 
 struct voxel;
 class Lightmap;
+class ContentLUT;
 
 struct RenderData {
 	float* vertices;
@@ -76,6 +77,8 @@ class Chunk {
 
 	ubyte* encode() const;
 	bool decode(ubyte* data);
+
+    static void convert(ubyte* data, const ContentLUT* lut);
 };
 
 #endif /* VOXELS_CHUNK_H_ */
diff --git a/src/voxels/WorldGenerator.cpp b/src/voxels/WorldGenerator.cpp
index 7fdb3ec82..4bc855e46 100644
--- a/src/voxels/WorldGenerator.cpp
+++ b/src/voxels/WorldGenerator.cpp
@@ -175,7 +175,7 @@ void WorldGenerator::generate(voxel* voxels, int cx, int cz, int seed){
 			float hum = fnlGetNoise3D(&noise, real_x * 0.3 + 633, 0.0, real_z * 0.3);
 			if (height >= SEA_LEVEL) {
 				height = ((height - SEA_LEVEL) * 0.1) - 0.0;
-				height = powf(height, (1.0+hum - fmax(0.0, height) * 0.2));
+				height = powf(height, (1.0+hum - fmax(0.0, height) * 0.1));
 				height = height * 10 + SEA_LEVEL;
 			} else {
 				height *= 1.0f + (height-SEA_LEVEL) * 0.05f * hum;
diff --git a/src/world/World.cpp b/src/world/World.cpp
index 042b2418c..3a1c8df32 100644
--- a/src/world/World.cpp
+++ b/src/world/World.cpp
@@ -6,7 +6,7 @@
 #include "Level.h"
 #include "../files/WorldFiles.h"
 #include "../content/Content.h"
-#include "../content/ContentIndexLUT.h"
+#include "../content/ContentLUT.h"
 #include "../voxels/Chunk.h"
 #include "../voxels/Chunks.h"
 #include "../voxels/ChunksStorage.h"
@@ -77,18 +77,18 @@ Level* World::create(string name,
 	return new Level(world, content, player, settings);
 }
 
-Level* World::load(path directory,
-				   EngineSettings& settings,
-				   const Content* content) {
-
+ContentLUT* World::checkIndices(const path& directory, 
+                                     const Content* content) {
 	path indicesFile = directory/path("indices.json");
 	if (fs::is_regular_file(indicesFile)) {
-		auto lut = ContentIndexLUT::create(indicesFile, content);
-		if (lut) {
-			throw world_load_error("world indices conflict");
-		}
+		return ContentLUT::create(indicesFile, content);
 	}
+	return nullptr;
+}
 
+Level* World::load(path directory,
+                   EngineSettings& settings,
+                   const Content* content) {
 	unique_ptr<World> world (new World(".", directory, 0, settings, content));
 	auto& wfile = world->wfile;
 
diff --git a/src/world/World.h b/src/world/World.h
index fee5ff362..ac37d5c21 100644
--- a/src/world/World.h
+++ b/src/world/World.h
@@ -13,6 +13,7 @@ class WorldFiles;
 class Chunks;
 class Level;
 class Player;
+class ContentLUT;
 
 class world_load_error : public std::runtime_error {
 public:
@@ -44,6 +45,9 @@ class World {
 	void updateTimers(float delta);
 	void write(Level* level);
 
+	static ContentLUT* checkIndices(const std::filesystem::path& directory,
+										 const Content* content);
+
 	static Level* create(std::string name, 
 						 std::filesystem::path directory, 
 						 uint64_t seed, 
@@ -54,4 +58,4 @@ class World {
 					   const Content* content);
 };
 
-#endif /* WORLD_WORLD_H_ */
\ No newline at end of file
+#endif /* WORLD_WORLD_H_ */